It's here! Run AppleTV as a standalone application on your Intel-based Mac!

(Sorry PPC folks, the binary on the AppleTV isn't Universal, its Intel-only, so you're out in the cold.)

Just download the torrent, and follow the instructions in the package! 

Credit goes out to Semthex for the patch for the AppleTV "Finder" and everyone in #osx86 and #appletv for their help (you know who you are).