DTCVersionManager is a free open source framework written in Cocoa/Objective-C for adding version management to any Mac application. It manages a full version history and informs the user of any new features since their current version, all in an intuitive and customizable interface. Here is the xml file upon which the versioning system for DTCVersionManager is based.
DTCVersionManager requires Mac OS X v10.2 or greater. The framework source also comes with an example project which requires Xcode.
This version is not tested nor guaranteed to work in Mac OS X v10.4. See "About" for more details.