[jsz0]

I can only think of two major hardware support issues:

-Graphics drivers. Google won't be using X so that will require some work. I imagine both Intel and NVIDIA will be happy to comply. Intel has a strong commitment to OSS drivers and NVIDIA can ship a closed source driver. No problems there.

-iPods. This one is tricky. They could rely on the existing OSS code but they risk breakage or support for bleeding edge devices. Google would be wise to approach Apple and try to work something out.

Everything else should be well supported by Linux. I was impressed that Ubuntu 9 fully supported my celluar data card including a nice setup wizard. Google should definitely keep this in mind for ChromeOS as 3G cards are probably among the most common devices attached to netbooks.