Reading Usable Help
@UsableHelp on Twitter
Gordon R. Meyer
Design notes for an iPhone tutorial
Matt Legend Gemmell writes about the design of his iPhone application, Favorites. He also describes his philosophy and implementation of Help and tutorials on the device. He even includes a movie of accessing the tutorial, which provides a nice in-context peek at how it works in the iPhone environment. (The tutorial movie is the last item on the page.)
See also Contextual Cues for the User for another project that uses Gemmell's design for onscreen text.