The approach I am thinking of for Media Portal to support touchscreens better is to expose the status info and controls to a network transport.
In this way we could use other software as remotes or touchscreens, this could be as simple as a web browser on the devise with a back end .net IIS server; or use other touch software like Promixis net remote or xlobby (althought that project is now commerial there is still the freeware version around that is the best touchscreen interface I have yet found).
This xPL technoligy looks interesting
XPL News - XPL
it has already been integrate into MCE
xPL Monkey - Home Automation - Windows Media Center