TimeMachineGrowler 1.0.2

On a stock Mac OS X system, you only know Time Machine is backing up when you hear your back-up disk start churning and see the Time Machine menu extra's icon start spinning.

This app polls the system log looking for messages from Time Machine, and translates them into Growl notifications for back-up started, back-up finished, and back-up canceled. The back-up started notification tells you how long since the last back-up finished, and the other two tell you how long the back-up ran for.