If you're eager for the possibilities for a fully app-enabled Apple TV, the jailbreak hacker geniuses are right there with you. Last week saw some proof of concept demonstrations from Steve Troughton-Smith and @TheMudkip, featuring native applications running on the iOS-based settop device.
The input mechanisms are a bit wonky at the present stage -- without a touchscreen, the devs need to use a combination of VNC, touchpad and keyboard inputs -- but remote support is on the way, they say. Troughton-Smith has released a UIKit library for other developers to play with, and the first third-party demo (a weather radar app) is apparently working now.
Now there's a nice high-def video demo, seen below, via MacDaddyNews, that gives a better sense of the capabilities of this hack. While some apps may appear sluggish, that's an artifact of the control scheme; the final product should be nice and snappy.
Jailbreaking the current version (4.4.4) of the Apple TV got easier last week, as the free jailbreak tool Seas0nPass was updated to allow an untethered jailbreak of the device. A jailbroken Apple TV can use third-party plugins such as XBMC, NitoTV or Plex.