Apple is posting the numerous developer sessions from WWDC 2011. You can view them by logging into the Apple developer site. There are 109 sessions total, and each covers an aspect of Apple development such as App Frameworks, General, Core OS, Developer Tools, Graphics, Media and Games and internet and web.
Again, you will have to register as a developer. The good news is that this is free–it’s not the same $99 as obtaining a license. You can view the videos here: Apple Developer Sessions.
It’s worth checking out if you are a developer or interested in creating content for iOS or Mac. Otherwise, it’s probably just a bunch of stuff that won’t make much sense.