After this version of the X Input extension missed the 1.10 cycle, it was getting back on track for a xorg-server 1.11 merge. The multi-touch work has already went through several revisions by Daniel Stone and Canonical.
This work was looking like it would finally land for X.Org Server 1.11 when it's released in August, but it doesn't look like it will make the merge window closing in a few weeks. One of the problems causing a delay in the merge deals with touchpads and where touch/mouse events are delivered to different windows.
Canonical is still working on the tool-kit support and gestures with X Input 2.1 and will continue to provide early back-ported patches into the Ubuntu 11.10 environment. Canonical had also provided early "prototype" patches for their multi-touch / gestures work into Ubuntu 11.04. Daniel Stone is the one driving the upstream work and actual development.
With Ubuntu 12.04 they may not even carry X.Org Server 1.12 depending upon when it's released and its quality, due to 12.04 being a Long-Term Support release. For even Ubuntu 12.04 this may mean back-porting the X Input 2.1 support once again if they will be shipping X.Org Server 1.11 instead.
Wayland was also brought up, but further investigation whether evdev events from the kernel will be enough there. An example Wayland client is needed to better determine its input needs.