I've been self-hosting on an IBM/Lenovo x41 for the last few months and have had very few issues. Specifically, the Trusted Platform Module needs a new driver for Vista and the Biometric scanner issue that I mentioned here are the only ones left outstanding.
Most frequently, for devices that are not supported "in-box", users will be able to check Windows Update and get the drivers needed.
Of course, with my feature being Touch Input, I have various touch-enabled devices that I use to test on, from a variety of manufacturers. I even have resolved the Fujitsu P1510d issues. There's nothing that a new driver, some BIOS tweaks and reg keys can't fix, ha!
If you attended WinHEC, you may have seen us demoing Touch Input on modified Motion LE1600s. This is what I'll be bringing with me to Boston for demonstrations.
Lastly, I'll let you in on a little secret. If you're like me, you wonder "what if I..." and then you do it if you can afford it. So my secret is, that I've been experimenting with putting Vista on a Samsung Q1 UMPC. While the experience is not seamless, and there is a whole lot of pain involved, it looks promising. I can even get the Touch UI to appear! I only wish the Q1 had specs a bit closer to what the Windows Vista recommendations say...