Since Nintendo's focus is on low power & form factor, I decided to look at this AMD GPU comparison chart
http://en.wikipedia.org/wiki/Comparison_of_ATI_Graphics_Processing_Units
Now, as I peruse through the interwebs for Wii U infos, I have noticed that NO ONE has seriously discussed MOBILE gpu as an option for Wii U. Why is that? Look at this card for example, seems tailor made for Wii U esp. if they customize it further:
Mobility Radeon HD 5830
lauched: January 7, 2010
40 nm, DX11/4.0 shader
800 GFLOPS
TDP: 24 Watts
Lots of people freaking out thinking Wii U will be weak b/c of Iwata saying the system is 75 W power consumption, but its still possible to have decent specs.