Not that I care too much about high def just yet, but I think it's worth pointing out that the Wii is technically capable of it.  Think about it, the Xbox apparently ran a few games in 720p (which games were they?), and the Wii has almost twice as much memory as the Xbox, plus is overall more powerful.  The Wii also can use component cables, the bare minimum connection required for HD.  All in all, the Wii should be able to pull off HD, just not all the time.  Perhaps a few top notch developers similar to Factor 5 will come along and push the machine enough to make it run in HD, who knows.