Apple has just released the WWDC 2010 session videos. A registered Apple developer account is required to download them, and you can find them at developer.apple.com/videos/wwdc/2010/. They’re available both in standard and high definition.
“Watch over 100 in-depth technical sessions from WWDC 2010. You’ll learn advanced coding techniques that will show you how to enhance the capabilities of your applications with the revolutionary technologies in iOS and Mac OS X. Download the videos, then take them with you on your Mac, iPhone, or iPad to watch anytime, anywhere.”