iH8sn0w has released Sn0wbreeze v2.9.3 update that includes support for Apple TV 2 for iOS 4.4.3/4.4.4 and integrated with some fixes for iOS 5.0.1 where it would halt on the Apple upon boot.
Just adding this in mainly for users who dumped their SHSH blobs. On the initial boot, the Apple TV may have a black screen for 60 seconds after setting up the Apple TV. This is normal.
Download Sn0wbreeze v2.9.3
See also:
How to Jailbreak iOS 5.1 with Sn0wBreeze
How to Jailbreak iOS 5.1 on iPhone 4, 3GS, iPod Touch 4G, 3G with RedSn0w