[aaronbrethorst]

Pete mentions both of those, and another (and gives me a nice shout-out) in the readme:

    There are some open source and commerical stacked implementations out there, yet none of them were flexible enough to fit my needs. Special thanks to Cocoacontrols for this article[1].

    StackScrollView (BSD)
    CLCascade (Apache 2.0)
    stackcordion.git (CCPL)

[1] http://cocoacontrols.com/posts/how-to-build-the-twitter-ipad...