We were surprised and disappointed to see that Google chose to equip its Chrome Notebook, the CR-48, with an Intel Atom processor rather than a more fitting partner like an ARM-based Samsung Hummingbird Application processor.
Going for an Intel processor makes it easier to develop, faster to roll out and mass produce; more importantly, it shows that Google wants to position the Chrome OS as a different proposition to Android OS, which is tied to ARM.
That said, Sundar Pichai, Google's VP, confirmed that the operating system is designed to work on different hardware platforms and it was actually the partners (Samsung and Acer) that opted for Intel, possibly because of the common platform (take a netbook, remove Windows, install Chrome).
Still, given that we previewed an ARM-based netbook back in August 2009, one that was manufactured by Pegatron, an Asustek offshoot, there's no practical reason why Google (or its partners) couldn't get Chrome OS to run on one.
What's more, going for ARM would certainly have cost less than adopting Intel; a system-on-chip like the Hummingbird or the Orion will always be cheaper than an CPU+Chipset combo and deliver better peformance per cycle.