We have absolutely no idea how many ALUs are in the GPU. None at all. We don't even know what architecture it uses, whether it's VLIW4, VLIW5 or something completely custom.
Everything on Gaf and Beyond3D is pure speculation.
All we know for certain is that it has 32MB of eDRAM, at least 1MB of SRAM, a DX11-equivalent feature set and a usable tesselation unit...and that it's more powerful than the RSX and Xenos.
How do we know that latter part above..? Trine 2 and Most Wanted are a noticeable step above the PS3 and 360 SKUs and the Japanese Garden and Zelda tech demos are beyond anything that RSX and Xenos are capable of in real-time.
And Ninja, your sig doesn't take into account several important things - Expresso has a shorter pipeline than Xenon, Xenon is In-Order and therefore less efficient, Xenon has to deal with sound, IO and OS whereas the Wii U has dedicated silicon to deal with these things, freeing up Expresso for other tasks.
In terms of real world performance the Wii U is around 3-4 times more powerful than the 360. We've gone over all this before mate.