There's another great conference coming before WWDC. It's one I won't be able to attend, but it looks pretty awesome. If you're in the UK or even from continental Europe and can't afford the trip to WWDC, NSConference may be an acceptable alternative to tide you over till next year.
It's not an official Apple event like WWDC so you won't get the benefit of talking to the Apple engineers or seeing Steve Jobs speak (assuming he does at WWDC, that is), but they've got a heck of a lineup of speakers including the incomparable Mike Lee (now an Apple employee), Bill Dudney, Matt Gemmell, Andre Pang, Frasier Speirs, Philippe Mougin, Graham Lee, Marcus Zarra, and Drew McCormack.
I rather wish I could go, to be honest. Maybe next year.