Short answer: yes and yes.
C++ AMP is an open specification so any 3rd party can implement it to support any kind of hardware:
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:
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.