This multi-touch support requires the Linux 2.6.30 kernel. How this works right now is by reading the input events, translating them into multi-touch events using simple gesture recognition, and then sending D-Bus messages over to Compiz to produce multi-touch effects. Right now the code is deemed just a proof of concept, but they are currently working on a better implementation. More information on their current Linux multi-touch work is available through the project web-site. Below is a video they had recorded yesterday showing off some of their multi-touch work on Linux.
Microsoft is already light-years ahead in this area with their Surface product. Multi-touch has also been receiving a lot of focus in the development of Windows 7 and MS recently showed off a collection of multitouch-exclusive softwares and games collectively known as the “Microsoft Touch Pack for Windows 7“. I hope Linux soon will be able to step up to the competition - game on!
More info: http://www.lii-enac.fr/en/projects/shareit/linux.html