This is a great resource:
Want to know how to write programs for the iPhone and iPod touch? Beginning this week, a Stanford computer science class on that buzzworthy topic will be available online to the general public for free. The 10-week course, iPhone Application Programming, is a hot ticket. It begins today and videos of the classes will be posted at Stanford on iTunes U two days after each class meeting (http://itunes.stanford.edu). Copies of the slides shown in class will be available there as well.