All of @kolpanic's handy-dandy tips for WWDC attendees in once convenient place!
You have to be at least an online member of the Apple Developer Connection to buy a WWDC E-ticket. Recent WWDCs have sold out, so it pays to shop early.
Also, if you're a student, Apple offers a limited number of scholarships consisting of free WWDC passes. Apple provides information on this and special student-related events at the WWDC Student Program site.
First off, you need a passport (or other accepted proof of citizenship) to enter the USA. If you have a passport, but its expiration date is in the next six months, you may have some difficulty using it. The good news is that the renewal process is now simpler. You have to meet some conditions, but the form is shorter and you don't have to submit proof of citizenship or get everything signed by a guarantor. If you're not renewing your passport, but instead getting a new one, the process has been simplified a bit by allowing many more types of guarantors (so you don't have to pay your doctor for the service).
If you're a tacowhand, you live in Southern Ontario, and that means you're going to fly from Toronto to San Francisco International Airport (aka SFO). Air Canada operates frequent non-stop flights to SFO (it's AC's only non-stop Bay Area destination) at various fare levels. If you're lucky enough to have accumulated some Aeroplan miles, you can get an economy-class seat for as little as 25,000 miles. Otherwise, if you can't get your employer to spring for for the airfare, you'll be better off checking out the various travel sites for the cheapest airfare. If you fly a U.S.-based carrier, you may have to connect in one of their hub cities. Another option worth investigating is flying out of Buffalo (to SFO, Oakland or San Jose, probably via a connection), driving there from Toronto and leaving your car in the long-term parking lot for a week. No matter how you get there, there are a few things you can do to ease your way.
First, you'll be bringing with you a lot of valuable gear and gadgets, right? Your MacBook, an iPhone or iPad, a digital camera, maybe a nice watch — a bunch of items that could pique the curiosity of a gung ho (or pissed off) customs agent upon your return to Canada. To bring them back without being hassled about buying them during your trip, you have to get a Form Y38, Identification of Articles for Temporary Exportation from the Canada Border Services Agency. The Y38 lists all the items you own and are planning to bring with you on your trip. You can get this at the CBSA office at the airport when you leave for California, but, if you're travelling on a weekend, it'll be understaffed and overwhelmed.
Instead, you can avoid the delay by visiting a local CBSA office ahead of time (in Toronto, the best bet is the office in the Government of Canada Building on the south-west corner of Front Street and Yonge Street). Bring the items you want to list. If you make your own list ahead of time, with a table of the items and their serial numbers, the agent can transfer all the information to the green cards, and you'll be on your way in a few minutes. Now there's no need to get to Pearson extra-early, and when you return to Canada, you don't have to sweat about being charged GST on a three-year old MacBook.
Finally, if you are flying out of Pearson, the GTAA has an up-to-date page with info for US-bound travellers here.
There are a number of ways of travelling from SFO to downtown San Francisco. The most obvious is a cab. That'll cost you a flat-rate of $35–40. You can also get a shared ride in a shuttle van for $15–20. However, I prefer to take BART, the extensive San Francisco-area subway system. BART has a station at SFO. You can either walk from your arrival terminal (about 10-15 minutes), or take the free SFO AirTrain. The trip from the airport station to downtown is only around 45 minutes, and costs $8.10.
BART is different from the TTC in that subway fares are based on the distance you travel. You feed a fare card with a magnetic stripe through the turnstiles both when you enter and exit the system, and the fare is deducted from what's encoded on the card. You can buy a card from the automated machines at any station.
If you have a friend in the Bay area with an available couch, get in touch now and nicely ask if you can crash there. Even the cheap hotels are expensive. In the past, Apple has negotiated special rates with some hotels (they usually list them somewhere on the WWDC web-site). Of course, if an associate is going too, you could room together and share the cost. If you don't mind shared bathrooms, there are some boutique-style hotels near Moscone, though the rooms tend to be small. CocoaDev has a page listing San Francisco hotels, arranged by distance from Moscone Center (though it may not be up to date).
Check the usual travel web sites for deals. BetterBidding is useful for decoding the anonymous hotel listings on Hotwire or Priceline.
There are also a number of hostels near Moscone. If you don't mind sleeping in a bunk bed with strangers in the room, your whole week's stay can cost less than a night at some hotels.
The weekend before the keynote, you can pick up your conference badge and paraphernalia — usually a t-shirt and laptop bag (though the old-timers remember the days of leather jackets and iSight cameras). Head over to Moscone West on the weekend, and go to the appropriate wicket for international attendees with your last initial and show your photo ID. Keep your badge safe! You'll have to wear it visibly at all times during WWDC events, and replacing a lost badge is pretty much impossible.
Apple provides a continental breakfast and cold lunches at the convention centre as part of the fee you paid. It's typical convention centre food — read into that what you will. They also set up mid-morning and mid-afternoon snack and drink stations.
Apple serves a buffet dinner at the Thursday Bash.
Apple usually sets up a WiFi network on each floor of Moscone West during WWDC. It's occasionally flaky early in the conference, but it usually gets reliable enough by the second day, though. For people who use ethernet or need to recharge their batteries, there's usually a lounge or two on each floor with ethernet cables and power strips (though they tend to be busy until they get the AirPort network up to snuff).
If you don't bring a computer/iPhone/iPad, you can still keep in the loop. There are usually banks of iMacs around Moscone. Just remember to clear any saved private information in whatever application you use. For example, with Safari, turn on Private Browsing before you check your web-mail, and, when you're finished, choose the Reset Safari option.
Note that a laptop is really useful for the hands-on sessions, where you code along with the presenter. You may also want to bring an external hard-drive or re-partition your internal HD before leaving home, in case Apple releases a preview version of a new OS.
The advice here is simple: get there early for a good seat. Doors open at around 7 A.M. (or earlier). You line up around the block outside, then they let you in and you line up at the first escalator, then they let you up to line up a couple of more times. Finally, they open auditorium doors, and there's a mad dash for seats.
The first few rows are reserved for VIPs and invited guests - convention staff will herd you away from that area. (However, a few years ago, we got seats about ten rows from stage on the side with the bank of demo machines, well within range of the legendary RDF. This was after a staffer said they had a couple of empty seats near the front they wanted to fill up for the cameras).
While Apple posts schedules at the public WWDC site, they usually have better, frequently-updated ones at the site for registered attendees. Once you've logged in, you can customize your schedule by adding sessions, labs and special events, then subscribe to it in iCal. Then, as Apple fills in the TBA blanks, update your custom schedule and refresh the subscribed calendar. (By the way, it's a good idea to turn on time-zone support in iCal's preferences, and switch time-zones when you get to San Francisco.)
In recent years, Apple has published a WWDC iPhone app, with up-to-date personalized schedules, maps and news.
Typically, Apple holds special events during the evenings of WWDC. For me, there are two must-attend ones: Stump the Experts and the Bash.
Stump (as it's known) is a chaotic Mac development trivia contest pitting the audience against a large panel Mac notables. If you pose a question that stumps the panel, or you answer one of theirs, you win a prize. It takes place in the main auditorium. Get there early, as it's quite crowded. In fact, you'll probably want to attend the Apple Design Awards too, because Stump takes place shortly afterwards, and you can keep your seat, or more easily move to a better one.
In the past, the Thursday evening Bash was held at the Apple Campus in Cupertino. However, with the growth in attendance, the logistics of busing everyone down to Cupertino probably got overwhelming. Now, it's held in San Francisco, usually in Yerba Buena Gardens, across from the Moscone Center. You can have a buffet dinner and a drink or two, maybe listen to a live band, and meet your peers and some Apple engineers.
When the bash was held at the Apple Campus, a highlight was the visit to the Company Store for souvenirs. If you can't make the trip down to the valley yourself, you can visit the Apple Store San Francisco, around the corner from Moscone West at Stockton & Ellis. It's a two-storey flagship store, and it's busy during WWDC.
However, if you do have some free time (e.g. on one of the weekends before or after the conference), you might want to make the trek to Cupertino anyway, though you'll probably have to rent a car. And, since you're already heading south, you might want to drive for about another hour and check out Monterey and Carmel. In the opposite direction, you can head north across the Golden Gate to Napa & Sonoma counties, California's wine–growing region.
If you haven't already seen it, the Alcatraz audio tour is really interesting. You have to take a ferry to the island, and the tour takes a few hours, but it's quite worth it. If that's not to your taste, visit the San Francisco Museum of Modern Art (SFMOMA) if only for the Museum Store. Finally, TripAdvisor has some other ideas for tourists in San Francisco.
If you're flying on Air Canada, make sure you're an Aeroplan member. If you're staying at a major-chain hotel, join their loyalty program, and instead of earning their points, choose the option where you can earn Aeroplan miles for your stay. Finally, get a credit card that gives you Aeroplan miles for spending money, and charge everything to it.
With all of that, plus the things you'll buy in the ensuing year, your next flight to WWDC could be free. Of course, you may not want to do this if you're not flying Air Canada, or you already have miles in another program, or another travel-miles credit card. However, Aeroplan is the only one I know of that lets you earn miles for actually flying, plus has all the links to the hotel and other travel affinity programs.