I just downloaded the iTunes U app for my iPhone and the first course I got into was the iPhone and iPad application development from Stanford. I find it an excellent primer for an initial foray into the world of iOS development and also an overview of the possibilities of the Xcode development environment.
Checkout the lecture on Xcode and source code management to see how well Xcode and Git are integrated. It makes my visual studio seem like tools from a distant past.
Has anyone got other suggestions for good courses to follow?