Michael Tsai with a round up of some talk from the Cocoa Dev email list. Everything I had heard previously suggested that there would be only a very minor (if any) performance implication from ARC. It does make sense that with the additional reliability and convenience would come some kind of performance penalty but I had not heard talk about it before. Please don't read this as advice to abandon ARC though! As with all performance issues, if you are concerned about this then you need to measure your own situation before working on it. If that involves a few additional __unsafe_unretained variables then fine but please don't turn ARC off!
Putting together an In-App Purchase implementation still seems more work than it should be and there are loads of helper classes around. This one by Hermes Pique is similar in functionality to many others but it stands out as it seems well designed and is comprehensively documented.
OpenEars is a library I have been aware of for a little while now but this week saw a significant release with the addition of Spanish recognition and synthesis. Support for multiple languages is a huge step forward for a framework like this and it all works offline as well. There is some seriously impressive technology here.
Need to tell if your app is running with the new iOS 7 UI? Pete Steinberger has the answer with a little code snippet which does exactly that. I love the name but he is absolutely right, it's legacy as of next week.