First the post from Neogaf of said details.

Technical Specifications
Processors
The CPU and GPU are built on the same package.
CPU: IBM PowerPC 7xx-based tri-core processor “Espresso” clocked at 1.24 GHz before the 3.0.0 update, 3.24 GHz after the 3.0.0 update. This is an evolution to the Broadway chip used in the Wii, is 64 bit and uses Power6 technote When IBM has said that Nintendo has licensed the Power7 tech from IBM, Nintendo is not using it for the Wii U, explaining its backwards compatibility.
GPU: AMD Radeon High Definition processor codenamed “Latte” with an eDRAM cache built onto the die clocked at 550 MHz before the 3.0.0 update, 800 MHz after the 3.0.0 update.

Ok, now let us unpack this a little. It is possible to do this through a system update, if the system was released under-clocked, which is the case for most electronics. Systems in the past have done this before, so this wouldn’t be the first. Knowing Nintendo, it wouldn’t be too surprising if they did this. My issue with this rumor is the size of the jump. I myself have never gotten into the nitty-gritty of over-clocking a computer, so I will admit I may not be the best source for this. What I do know, and anyone who can add can see, a jump of two GHz is huge. We could consider some part of this true. The update could have added a little something to the Wii U, but maybe not as much as this reporting is claiming.

Now, on a little side-note, if true, this could be a reason why we haven’t seen a ton of first-party games. Maybe all the upcoming Nintendo games are built around these higher speeds. Maybe some third-party developers know this as well..maybe…maybe…maybe.