Georg Kaindl, the guy who has written the Mac OS X multi-touch tracking software Touché has published Touchsmart TUIO. This is a piece of software, which produces TUIO messages on HP Touchsmart PCs (and any other NextWindow frame).
Thus, existing TUIO (multi-touch) applications like those from the nuigroup (which you can e.g. find here) can be used on HP Touchsmarts. Additionally, it allows the development of multi-touch applications on a small and reliable device. However, HP Touchsmart and the NextWindow frames have some drawbacks, which Georg presents us in his video about Touchsmart TUIO (with his charming Vienna accent):