Touchkit, a open source (software and hardware) multitouch kit designed by NOR_/D, has been announced at a $1580 price point, or roughly 1/8th the cost of Microsoft's Surface table. That's not to say that the TouchKit is equivalent or even necessarily a competitor to Microsoft's offering, but it is theoretically capable of many of the same flashy tricks. The system must be hooked up to a separate computer, and also requires an external projector. As you can see in the video, there's not exactly a whole lot it can do out of the box, but the open source platform can be tweaked by anyone with a little knowledge of C++.
Source: gizmodo.comAdded: 3 September 2008