Wii is actually 460p.
Good point, when it's progressive yeah. Interlaced it can be 576i. Not sure what mode it's in when in one of the "channels" rather than in a game. 460p looks better though over component than 576i.
The bottom line, is the Wii does not have the "grunt" to decode H.264, but the PS3 can do it in it's sleep..
Apples and Oranges. The PS3 is hugely more expensive and is a mini home computer/media centre/games console/blu-ray player. The Wii is a simple fun family entertainment console. Still, the Wii remains more popular as it appeals to more than the teen to 20-something boys and to a population who really don't give a rats about HD. For gaming, whilst an HD Wii would be nice, I agree. I really don't need an HD noisy power beast of a console, mainly because I just don't play those type of games enough to justify it.
For iPlayer I just use my netbook upscaling to 1080 to my TV. Low powered Atom processor (much lower than a PS3), low noise, and plays standard def iPlayer fine (would do HD also if BBC didn't use DRM protection. Unfortunately the brilliant Core AVC codec doesn't work with DRM content).
Actually, I bet if Nintendo licenced Core AVC it would play iPlayer fine in H.264 too. The Core codec people are currently adding more hardware and many embedded devices are using it now.