This is a minor update, basically bug fixes. However, we did take the opportunity to convert it to Automatic Reference Counting (ARC). It really was as easy as it looked in the ARC WWDC session.
I highly recommend watching that video if you're considering moving to ARC, as well as reading the Transitioning to ARC Release Notes, and the llvm ARC page. Bookmark that last page, because though it might be rough reading all the way through, it's a very handy reference.
I had planned on posting some tips and tricks regarding converting to ARC, but truthfully, I don't have any. It was simple, and pretty much just worked.