This rumor seems unlikely, like all the others so far, but an actual developer working on a known game has said the WiiU is pretty much on par with the PS3 and 360.
http://www.eurogamer.net/articles/2012-03-26-darksiders-2-dev-wii-u-hardware-on-par-with-current-gen
"So far the hardware's been on par with what we have with the current generations. Based on what I understand, the resolution and textures and polycounts and all that stuff, we're not going to being doing anything to up-rez the game, but we'll take advantage of the controller for sure."
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"When I was a young man, I had liberty, but I did not see it. I had time, but I did not know it."