Based on the update by FireCore, this was expected to release next week, but the GreenPois0n RC6 for Apple TV 2G untethered jailbreak has now been made available for download by Chronic Dev team. Owners of the 2nd generation Apple TV on iOS 4.2.1 can now jailbreak their devices, untethered thanks to the GreenPois0n RC6.
You can download it from the following links
Green posi0n for windows
You can download it from the following links
Green posi0n for windows