"Apple today announced that YouTube is now live on Apple TV.
Users can download the free software update using Apple TV’s built-in
software update feature, and then navigate through YouTube’s familiar
video browsing categories or search for specific videos. YouTube
members can also log-in to their YouTube accounts on Apple TV to view
and save their favorite videos." [Podcasting News]

Haven’t tried this yet, but I will. Stay tuned. Related story.