We've tried this before and the graphics drivers are the big pain. Got an Atom processor and their GMA500 graphics were such a pain to get working.
Linux users: watch out for last-gen Intel Atom
It hit the market during the last few weeks. Last generation of Intel Atoms: CedarView (D2300, D2500, D2550, D2600, D2700) and Cedar Trail (N2600, N2700, N2800) SoCs integrate a PowerVR GPU from Imagination instead of the usual Intel GPU. If you remember the Poulsbo fiasco, it's the same. More or less.
An unsupported graphic card on Linux distributions, and which can't properly support a basic desktop environnment like Unity or Gnome 3.
To prevent this issue, Intel woke up MeeGo from the dead in last february to add support for CedarView. And to publish the proprietary Linux driver, in a fairly exotic fashion. This driver is only available in MeeGo repositories. Upstream First? It doesn't seem to be a priority.
Note that this proprietary driver requires adding a 100k+ line patch to the kernel. Available only in the MeeGo source rpm, of course.
My personnal advice is to look at AMD's offering: the Fusion line up is starting to be very well supported in the upstream open source stack(kernel/libdrm/ddx/mesa), as long it's up-to-date. from Linux users: watch out for last-gen Intel Atom
Next gen Atom (ValleyView) should have a "classic" Intel GPU from IvyBridge. But they won't be widely available before 2013, so until then, you should be careful. from Linux users: watch out for last-gen Intel Atom
Intel will offer three versions of Valleyview-based platforms: Bay Trail-T (3W), Bay Trail-M (4W – 6.5W) and Bay Trail-D (12W) for tablets, notebooks, and desktops, respectively. from Intel’s Next-Gen Atom “ValleyView” to Double CPU Performance, Triple Graphics Performance - X-bit labs
But since Bay Trail is not yet available, what's a good test bed. Well maybe the current line of Haswell mini-ITX boards is one place to try.