Looking at AMD's first combined CPU/GPU products (which they call APUs) the AMD Embedded G-Series has left me considering how ARM and X86 design seems to be crossing paths at this point.

http://www.amd.com/us/Documents/49282B_Embedded_Solutions_GSeries_Brief.pdf

Nvidia's Denver might be 64 bit and in some ways resembles what AMD is considering. After consideration, while I am unsure about whether or not Denver will be 64 bit or not, but I'd think its fair to say that it isn't likely to clock above what current A9 are being tested at. It probably won't be a complete SOC like most current ARMs (since much of that functionality would be wasted in servers).
And they may focus on two things that aren't common in ARM design. First a better interconnect system like AMD licensed Hyper Transport interconnections. And second GP GPU computing. After all Nvidia has been pushing this and in a servers the GPU part of an APUs would be largely wasted.

As these two ISAs grow to resemble each other architecturally, its going to be interesting seeing how each fairs in competition with the other.