Whislt i like the idea of AROS/MorphOS or indeed any Amiga/AmigaLike OS running on the Wii there are some points i've gotta disagree with.
Firstly the Gekko was based on the G3, and whilst it does have some SIMD style instructions they're massively different to Altivec. If anything they're more like the PSPs vfpu instruction/unit in that they're highly specialised just for matrix<>matrix, matrix<>vector and vector<>vector operations.
Next; the G4 is dead? Hardly, the G4s used by Apple/A1 etc were all chips based on the e600 core and varied wildly in the performance of those implementations. The 8641D which they're just making available as engineering samples is a fairly high performing version of the e600 core (two of them in fact) with an intergrated DDR2 memory controller and Altivec. So the G4 series of chips is hardly dead.
Also the 750CL is just as i described. It's a die-shrink with a higher clock speed, double i think. Oh and the ram isn't 1T-SRAM, it's GDDR3. Main memory doesn't seem to have changed at all.
Lets make something clear, I think that it'd make another great target for things like AROS and the other to run on. But dont over sell it, it's not as great a CPU as it could have been and the GX doesn't even have shaders like a £20 modern graphics card or run as fast, also the amount of memory is a bit pants.
However it's going to be a very cheap and incredibly popular piece of hardware that everyone and there pet is going to own :-D
Andy