The Apple iPhone SDK is apparently going to become quite important to teaching CS and Digital Media largely because this is a platform that students are interested in exploring.
Questions to explore:
Even though the Apple docs continually refer to the language as “simple” the main issues appear to be the unfamiliar syntax, the message-passing model of invoking object methods, and the C memory-management model using pointers, which always tripped up a good number of my intro C++ students. Note:I haven't read the garbage-collection paper yet.
One approach to questions 1 and 2 might be to give a few students with differing programming backgrounds a crash course in the syntax of Objective-C and evaluate how comfortable they are discussing the source code of a sample app. Or dispense with the crash course and just see how they do talking through what is going on in a short Objective-C sample.
Some Approaches to #3, some of which may already be out there:
Inside the iPhone SDK (Ars Technica article)
Stanford CS course on iPhone SDK programming
News Item Apple's university program
Apple's Intro to Objective-C
Apple's Guide to Object-Oriented Programming in Objective-C
iPhone Development book from O'Reilly