I really like what they did with the Metroid Prime 3 Preview channel as-is. It's a separate little applet that has a Metroid-esque look and feel -- having the videos on a generic Wii Preview page wouldn't be nearly as buzzworthy. Even though it's just a simple title screen, menu, and a revealable image, it still takes the viewer from the Wii look-and-feel into the Metroid universe briefly.
And I really like the trailer -- first time in a long while the Nintendo logo has appeared in a very cool context.
It's just an ad but it's nice to see something new (better than those VHS tapes Nintendo used to mail out in the N64 days...)