Well, it's already happened again. GreenpoisOn has broken iOS 4.2.1 with an untethered jailbreak for AppleTV called RC6.
An untethered jailbreak means that the jailbreak persists through a reboot, making it a useful one for the jailbreak community, since the current offerings only have jailbreaks that vanish when you power off the box.
NitoTV, a weather app that ran on the original jailbreaking of the AppleTV back in October helped with this, and that software package is auto loaded with the hack. As always, jailbreaking your device can make it a paperweight and void your warrant, so proceed at your own risk.
I don't actually own an AppleTV box, but it was something I was definitely looking into before tablet frenzy took a hold of me. These days I'm not sure I could justify it, unless I got it specifically to run hacks like this. With Netflix and other streaming services, I'm not sure I really need to be paying out for another set-top box for shows I never end up watching.
What about you? Do you own an AppleTV? If you do, is it already jailbroken? Will you be running Greenpois0n? Is it worth it?