The recently released Greenpois0n jailbreak tool has been updated to release candidate 6 today, and this particular version will allow you to jailbreak your second-generation AppleTV and install the popular NitoTV software, adding a few great new features to your device.
The process is exactly the same as that used for release candidate 5, and just as before, this will provide an untethered jailbreak for all devices, meaning you won’t need to plug them in to your computer when you want to boot them.
Greenpois0n RC6 is available for both Mac and Windows, and you can download it now from here.