Practically since the launch of the Wii, analysts and wishful (or dissatisfied) Nintendo fans have been speculating about when we'll see a high-definition version of the console--and what the original Wii would have been like if it had been capable of HD graphics in the first place. Take a look at the video below (and ignore the dubious legality and complete absurdity of someone reviewing an emulated version of a two-year-old game) for a glimpse at what Super Mario Galaxy might look like running in 720p.
It's probably a testament to the quality of Nintendo's art assets that the game looks as good as it does with the resolution boosted. It's pointed out in the video's comments that the jerky frame rate is due to the FRAPS recording software used, but this gives you a pretty good idea of what a backwards-compatible HD Wii might look. Of course, Nintendo has said nothing to that effect yet, but you can bet your sweet derriere that people will keep speculating about it until they do.