A mysterious gap in the Wii's feature list over the last couple years has been the lack of DVD playback. There's no technical reason it can't do it: it just doesn't. Not a big deal when a host of DVD-reading devices crowd in the nethers of the entertainment center: it's just a bit conspicuous of a corporate decision.
If you happen to have been waiting for DVD playback functionality on the Wii, the omission has now been rectified by plucky hackers.They have come up with a way to read and play DVDs on unhacked systems. Their DVDX installer injects a small hidden channel onto your Wii that will allow you to play DVDs back with MPlayer, a GPL media player.
Neat. In truth, of all the consoles, I'd probably prefer to play DVDs on my Wii: the Wiimote is a far more remote-like controller for movie playback than a clunky 360 controller.