This is Github Growler: fetches GitHub timeline and growls as new activies are coming in.
There's a binary build for Mac OS X Leopard available at Downloads.
If you're trying to run this on other platforms, just run github-growler.pl. You might need to install its CPAN module dependencies with cpan -i . command.
You need to set github.user and github.token in your global git config or pass them to the command line arguments.
By default this scripts fetches the github updates every 300 seconds and displays at most 10 Growl notification per fetch and you can change the both settings with Mac OS X preferences:
defaults write net.bulknews.GitHubGrowler interval 180
defaults write net.bulknews.GitHubGrowler maxGrowls 5
