We know that MuscleNerd was showing off his brand new jailbroken iPod touch 4G the other day. Looks like the same iOS vulnerability has just been used to jailbreak a second-generation Apple TV. After successfully using the SHAtter exploit MuscleNerd posted video of the Apple TV being accessed with ssh.
SHAtter tricks the Apple TV into restoring with a pre-jailbroken IPSW from PwnageTool. The same exploit should work across all iOS devices including the iPhone 4. Chronic Dev Team members are developing jailbreak tools for public release based on the SHAtter bootrom vulnerability. This method will be much more difficult for Apple to contend with, as a firmware update can't prevent the issue.