Mac users interested in Atvcloner update generally download:
AtvCloner is a Macintosh application that can be used to properly image the AppleTV1* hard drive and then partition a new drive for upgrading/replacing the built in hard drive in the AppleTV. This software will not work on the AppleTV2. AtvCloner is tested using Mac OSX Leopard (10.5.xx) through Mac OSX Snow Leopard (10.6) but will not work with 10.4 Tiger.
