Youve never heard of the red ring of death? Thousands of people had their 360's overheat on them while playing games.
Less than half 3.2 Ghz. He was under NDA and did not want to say anything that would upset Nintendo. Saying the system ran at 1.25 Ghz, or even a ballpark number anywhere CLOSE to what the real clockspeed was would have been unacceptable. Saying it is less than half the speed would have been a bad move because it would have pissed off Nintendo. Making an extremely vauge maybe a little slower comment was pretty much the best he could do at the time beyond no comment, 360 code is no good for the wii u cpu. The architectures are complete opposites, 360 used simd to break instructions up over many parallel taskings and used a high clock speed to compensate the slower instructions per clock that resulted. espresso completes many instructions in whole chunks at the same time, completing many many many more instructions in a single clock than xenon (18 instructions per clock compared to xenons 6), but it is clocked slower. Keep in mind the 360 cpu is a g5, despite all the idiot port devs (mind you, its ONLY and ALWAYS port devs) masturbating to how awesome it is because it has a high clock speed, this is the garbage cpu that nearly destroyed ibm. Apple terminated their contract with ibm because of the crap performance of the g5. They wanted more advanced versions of the G3. Their ENTIRE ADVERTISING PITCH they built up over years, including demonstrating concepts like the Megahertz myth was designed around high ipc machines with lower clock speeds, the g3 was the power mac poster child. The G5 was the complete opposite of all that, couldnt come within a moonshot of its theoretical peak in real world performance, and suffered ridiculous penalties. The G5 is the reason icore exists. apple dropped ibm and signed on with intel creating the icore series.
You cant port that crap to the wii u and expect it to be easy peasy to get as good or better performance. It RELIES on the higher clockspeed just to work. Modifying the code will only get you so far, it needs to be completely rewritten on the instruction level because of how different the cpu's are.
Nintendo didnt bring it back from the dead. IBM did. IBM developed some manner of technology, most likely their new edram that acts like 6tsram technology that enabled them to achieve worthwhile smp on short piped architecture.
But brought back from the dead it most certainly was. IBM officially terminated the 750 family in 2006 with the FX/fl being the last in the family line ever documented. A single core processor that could BARELY make it to 1 Ghz, but wasnt advised to be used at such speeds.
the 750 is a descendent of the 740 which is a descendent of the 603e, the 750 had several generations itself, the 755, the 750 CX, the 750 cl, the 750 CXe (Gekko) The 750 CLe (broadway) the 750 FX, which could reach 900 Mhz, and has nearly twice as many transistors as broadway (this was 2002) in 2004, the last and most powerful 750 family was released, the 750 GX, with 44 million transistors, it had a little over double the transistors of broadway (which was a 2006 special nintendo and ibm collaboration from a team called team nintendo) and could BARELY reach 1 Ghz.
Thats it, aside from broadway, which was just an older cpu made on a smaller process (there were two generations of newer more powerful 750's when broadway was made), there hasnt been a new entry in the 750 line. IBM stopped documenting the 750 line, and publicly announced its plans to terminate the line, stating it would never make a 750 smaller than 90nm, smp was never achieved, and it was phasing it out as a commodity chip.
This is most definately necromancy. This line was deader than a doornail. Something made it viable again, and it wasnt Nintendo.
All in all I think Wii U will be fine. Up to the devs which is SCARY to think about.