AFAIK, the way ubuntu is doing it is only a stop gap. Qt did their own thing as well for multi-touch gesure support. The multitouch xinput2 stuff is still young and when it matures, both gtk (which is what ubuntu is focussed on) and qt will have to refactor their code.
MeeGo today has gesture support and can do multi-touch gestures as long as the driver works in such a way that Qt expects.
Former author of LinuxICE, nghost, nobdy.
Current author of Automotive Message Broker (AMB).
Works on Tizen IVI. Does not represent anyone or anything but himself.