The macgrowl package is a high-level Tcl wrapper for the Growl notification system on OS X (http://growl.info ). It interfaces with Growl via AppleScript, and provides hooks to post Growl notifications. (Growl also comes with an older Tcl binding that requires building from source, but it is unsupported and will not compile against recent versions of Growl.)
Macgrowl is developed by Kevin Walzer and is available at http://opensource.codebykevin.com .