YouTube XL: YouTube launches TV sized video browser
YouTube XL is essentially a front end for the main YouTube web site. You can watch most (but not all) of the videos found on YouTube using YouTube XL. And since it should work on any device with a web browser, you should be able to use YouTube XL with video game consoles that have web browsers, like the Nintendo Wii.
CNET reports you can't watch premium TV shows or movies on YouTube XL yet because Google is still working out licensing rights for that content.