
I played around with it today, and it seems to work pretty well. However, a new app called Hiss seeks to unify the two systems by putting your Growl notifications right into your Mountain Lion Notification Center. Growl uses its own banners and a “Rollup” window (a place to collect missed notifications), so it seemed the overlap was too large and there would only be room for one notification system on OS X. When OS X 10.8 was announced, many people assumed Growl was dead.

I have used it for years, and it is supported by a vast majority of Mac apps, including high-profile ones like the official Twitter client.

Growl is a notification app for OS X that predates the idea of Notification Center on OS X or iOS.
