Hi Walker
Short answer: yes and yes.
Longer answer:
C++ AMP is an open specification so any 3rd party can implement it to support any kind of hardware:
http://blogs.msdn.com/b/nativeconcurrency/archive/2012/02/03/c-amp-open-spec-published.aspx
But you are of course asking about Microsoft's implementation, and yes in our first release we run on DirectX 11 targets. One of those DirectX 11 targets is WARP:
http://www.danielmoth.com/Blog/Running-C-AMP-Kernels-On-The-CPU.aspx
What my blog did not state because it wasn't known at the time (I will amend it at some point), is that WARP indeed runs on ARM, so yes, your C++ AMP code will run fine on ARM based CPU.
Cheers
Daniel
http://www.danielmoth.com/Blog/