The AddressBook Objective-C wrappers for iPhone are now in their own project. The reason for this is twofold:
1. The AQToolkit is based around hybrid code which can be used on both the Mac and iPhone. This wrapper API, by its very design, works only on the iPhone - it uses the iPhone-only AddressBook framework, which has C APIs in the same header files used for the ObjC versions on the Mac. This makes it difficult to build AQToolkit as a complete library (my testing stuff is actually based around 10.5 and 10.6 builds, not iPhone).
2. The classes in this API are useful enough on their own, and involve enough classes, that it seems a good idea to separate it out from everything else in this generic toolkit project.
If you want the latest code (this move coincides with a minor update to the code itself) then you can find it here.