Apple has let iPhone, iPod touch (and Mac) developers know that World Wide Developers Conference (WWDC 2009) Sessions are now available for purchase via developer.apple.com:
Watch Apple engineers deliver in-depth technical information on the technologies that power iPhone OS and Mac OS X from the Worldwide Developers Conference 2009.
In addition to the session videos, you’ll also receive access to the presentation slides and sample code so you can make the most out of each session.
After your purchase, download the videos through ADC on iTunes, then take them with you on your Mac, your iPhone, or your iPod touch to view anytime, anywhere.
Costs are $299 each for iPhone or Mac sessions, or discounted to $499 for both.
See the iPhone session list (PDF link) for info on what's included.