Go to the Stanford University site:
http://www.stanford.edu/class/cs193p/cgi-bin/index.php
They ran a 10 week class on programming for the iPhone (1 hour @ 2x per week). The class was run by two guys from Apple. Every class was video recorded and posted on iTunes. In addition, every demo/project - with source code - was also posted. you can download everything from that site.
The class was top-notch, and for the low, low price of
FREE, you are getting all the material that students of Stanford PAID to get.
Please note that this material will NOT stay online for very long. From the Standford site:
"The content will remain available for most of the summer, but towards the end of the summer it will be taken down and the materials will no longer be available. It would be a good idea to download all the materials you need now so that when the website is cleaned you're not left missing stuff. Once it's gone, it's gone."
So, get all that material
NOW!
Also - and this is obvious - make sure you get XCode and the iPhone 3.0 SDK material from Apple. You'll need it if you want to write the code that was presented in the class - and of course, for your own development work. To get started, you
don't need to spend the $99 to register as a developer.
There are also books on programming for the iPhone; however, I would start with watching the Stanford videos and see what you think.
Good luck!
--DotComCTO