For reference, the 360 and PS3 CPUs run around 3.0 GHz, albeit carrying different core and thread capabilities. Eurogamer effectively called the difference a "wash," noting the 360 processes threads of information at approximately 1.6 GHz. Marcan also noted he thought Wii U's core design was "saner" compared to the 360 and PS3.
Meanwhile the GPU powering Wii U carries the codename 'Latte', and runs at a speed of 549.999755MHz. Wii's 'Hollywood' GPU clocked at 243 MHz, and the GameCube, 162 MHz. The Xbox 360 GPU speed is 550 MHz.
That's a lot of numbers, but it's safe to say that more and more evidence is placing Wii U alongside Xbox 360 and PS3 versus a drastic leap over the current generation. Developers are definitely coming to terms with what Nintendo's new system will be capable of, but it's also clear that Nintendo's divergent approach has once again focused on finding innovation in control and software versus attempting to compete in terms of raw power. As Marcan concluded, "...don't compare [Wii U] clock per clock with a 360 and claim it's much worse. It isn't."