If I recall correctly, Motorola designed it, IBM manufactures it. The gamecube used the medium level processor in the series, the Wii uses a higher end from the same series, with some tweaks I've heard. Kinda like going from a Intel P2 @ 500 to a Intel P3 @ 750 or so. The tweaks can help considerably (like MMX eventually did), but only if they're taken advantage of. So technically, depending on how different the processor architecture of a "WiiHD" processor, they would at least need a mild level of "software emulation" like the 360, or an existing "Wii" processor in addition to the new one ala PS3. I haven't heard about Motorola having anything higher in the same series of processors, so I don't see a lot of options there. Looks like EA is gonna be the first to release a "significantly upgraded gamecube engine game" for the Wii with SSX Blur, as far as I know Sonic is a new engine, so that's a bit different. (SSX Blur supports 16:9 and Progressive Scan, apparently does 60fps in single player, probably 30 in 2-player split screen I'd presume since he didn't mention it. http://wii.ign.com/articles/764/764416p1.html
Nobody is crazy enough to accuse me of being sane.
