Keith Harrison on probably the simplest of all of the iCloud APIs, preference syncing.
Amy Worrall on wrapping text to complex regions with Core Text. Surprisingly simple code for what could have been a really tricky problem to solve.
Tony Ngo with a short tutorial on integrating the new iOS 5 Twitter functionality. The only thing that annoys me about the iOS Twitter integration is that the app name always shows up as "iOS" rather than the app name.
I love that we have access to Core Image in iOS 5, but I had no idea it could do face detection. Krzystof Kunowski takes a look at CIDetector.
I came across this neat little library this week which gives a cleaner way to create multi-stage animations on iOS 4. If you are looking for the code, check the comments for the repository link as it is not linked from the main post.
Mugunth Kumar with an interesting approach to supporting the new iOS 5 JSON framework.