Before some hours, MuscleNerd has posted on this Twitter account stating that he has successfully jailbroken the Apple TV using SHAtter exploit and a custom IPSW using Pwnage tool. On the tweet, he also mention that he doubt about running iOS apps. But looking at this scenario, we can soon hear some good news on running iOS apps on the jailbroken Apple TV. There is no confirmation on the public jailbreak release, however now we are atleast sure of Apple TV jailbreak.
The Dev team has also updated with a video. Have a look it here