If you saw the video from last week, it won't be a surprise that this week saw the release of Facebook's animation framework taken originally from the Push Pop Press apps, Pop. The API is very similar to that of Core Animation so the learning curve should be pretty smooth and Kimon Tsinteris gives us an introduction in this post. If Facebook keep this level of quality open source release up much longer then soon I'll need to forgive them for Three20 😉.
Ole Begemann with a Mike Ash style "Let's Build" for Scroll Views. If you ever needed clarification on the differences between frame and bounds, building a scroll view is the perfect illustration of it. Ole's final product is missing many of the niceties of scroll views like inertia and bounce animations but it's impressive what can be achieved with only a few lines of code.
Kim Pedersen with a fascinating article on automatic generation of level data. This isn't going to be the kind of thing you get to use every day but I found the article a really interesting read. You will also want to check out Part 2 when you're done.