This post gathers interesting resources I found for the fall 2011 course.
The official material can be found on the course website at Stanford and on iTunesU. These lectures are based on Xcode 4 and iOS 5, so the older solutions are no longer applicable. There can be some help found in a corresponding Google Group.
There are multiple people that I are following the course:
I found various solutions on the web, which work as inspiration. You can find my solutions on Github.
Assignment 1 (Simple Calculator)
Assignment 2 (Programmable Calculator):
Assignment 3 (Graphing Calculator):