Recently Apple released iOS 6.1.2 to fix minor bug. Later, team evad3rs who is responsible for the untethered iOS 6.0 jailbreak released their evasi0n ver 1.4 for this jailbreak. However 2 days later they released evasi0n 1.5 to fix device restarting/crashing during jailbreak.
Apart from evad3rs, another jailbreak tool for iOS 6.1.2 was released by iH8Snow under the name sn0wbreeze. However, this jailbreak tool is only available for window users. Comparing sn0wbreeze and evasi0n, the latter is much easier with one click and ported to Mac, Window and Linux while sn0wbreeze requires too many steps including manually going into DFU mode.
Bad news for ATV3 owner because there seems to be no exploit to jailbreak the Apple 1080p unit. Airplay from jailbroken iDevices still works unless Apple did something to prevent this.
Before this, Santa was expected to deliver the exploits, yet the water snake couldn't help santa to deliver the ATV3 exploits, so we guess it is still a long way to go for ATV3 jailbreak!