Check out this Microsoft video of touch features in windows 7. It will be interesting to see how many car computer developers and touch screen fleet users implement these new features in their applications. The video certianly makes it look easy. More details are on the "Touching Windows 7" blog.
I was tempted to buying an HP TouchSmart PC to play around with the multi-touch support. If you install Win7 on these, they have multi-touch right off the bat.
We just need Xenarc and Lilliput to start releasing some multi-touch capable screens now.