Commit 2ace610 to the Qt Git repository extends the touch events for Qt 5. This very large commit now allows touch events to express velocity, differentiate between touches with a finger or pen, raw positions, and more. Introducd as part of this commit is a new QTouchDevice class.
From a mailing list message, "The touch event API had been extended to make way for multi-touch, differentiating between pen and finger, velocity etc. I hope there is a working high-level API :)"
As part of X Input 2.2, which should be integrated into X.Org Server 1.12, there should be proper multi-touch support on the X side. The GNOME developers working on GTK+ have also been looking towards input improvements.