"Blocks are a great addition to Objective-C, but unfortunately, are only available in Mac OS X 10.6. We have a quite a bit of code that could be greatly simplified using blocks, and so I decided to spend some time back-porting block support to iPhoneOS 3.0 and Mac OS X 10.5.
"The result, Plausible Blocks, provides a drop-in runtime and Xcode compiler for using blocks in your iPhone and Mac OS X 10.5 applications, based on Apple’s Snow Leopard blocks runtime and compiler support."
