Information regarding our hg repositories and other areas of interest are addressed in the developer documentation. Growl requires Xcode 3 to compile, which is available for free from Apple.
The Growl SDK, including frameworks for Cocoa and Carbon and bindings for other languages.
A simple Growl AppleScript example script that registers and posts a couple of test notifications.
The Xcode projects, source code files, and resources that comprise the current Growl release.