Apple has released the session videos from WWDC, available in HD through iTunes with accompanying PDF slideshows and sample code. They are formatted to work on the Mac, iPhone and iPad, and offer tips and tricks to improve your mobile and desktop apps. Registering to be a developer is free, and just requires a quick questionnaire. Videos include sections on Developer Tools, Graphics and Media, Application Frameworks, and more. You can also view the 2010 Keynote in full, featuring the iPhone 4 and iOS.