Apple is in the process of posting videos from the WWDC 2011 on iTunes and Apple's developer page. The video page was updated briefly yesterday, but the videos were never posted but we have confirmed that they are available on iTunes.
The videos can be accessed by registered developers by visiting the Development Videos page and clicking on "Log in to iTunes" on the bottom left.
The videos can be downloaded in standard- or high-definition. HD videos can be viewed on a Mac, iPhone 4, 4th gen iPod touch, iPad or Apple TV.
Article Link: Apple Releases WWDC 2011 Session Videos