"IBM's "Broadway" CPU is clocked at 729MHz, according to updated Nintendo documentation. By comparison, GameCube's Gekko CPU ran at 485MHz. The original Xbox's CPU was clocked at 733MHz. Meanwhile, Xbox 360 runs three symmetrical cores at 3.2GHz."
"Revolution's ATI-provided "Hollywood" GPU clocks in at 243MHz. By comparison, GameCube's GPU ran at 162MHz, while the GPU on the original Xbox was clocked at 233MHz. Sources we spoke with suggest that it is unlikely the GPU will feature any added shaders, as has been speculated. The 'Hollywood' is a large-scale integrated chip that includes the GPU, DSP, I/O bridge and 3MBs of texture memory."
Matt also goes on to write:
"Revolution will operate using 24MBs of "main" 1T-SRAM. It will additionally boast 64MBs of "external" 1T-SRAM. That brings the total number of system RAM up to 88MBs, not including the 3MB texture buffer on the GPU. By comparison, GameCube featured 40MBs of RAM not counting the GPU's on-board 3MBs. The original Xbox included 64MBs total RAM. Xbox 360 and Playstation 3 operate on 512MBs of RAM."
So it's pretty much confirmed that the Revolution is a direct extension of the GameCube hardware, just upgraded, without all of the bells and whistles Sony and Microsoft seem to think that are needed in their next generation of consoles. All the specs in the world don't matter unless you have engaging titles on your console and thankful that has never been a problem when it comes to the house Mario built.