I just found this nifty PHP class for sending growl notifications from sitecrafting.com.  Very nifty.  Here’s some sample code to get it going:

// Setup
$growl = new Growl();
$growl->setAddress('127.0.0.1');
$growl->addNotification("Test");
$growl->register();

// Send Notification
$growl->notify("Test", "Test Alert", "The body of the test alert!");