Linux has been capable of driving multitouch trackpads for years (specifically the synaptic driver). Even then, it can 'fake' it on some, by detecting the width of the touch area. The main problem is all the touches must be handled in the driver, so pretty much only two finger scrolling, two finger click for right click and three finger click for middle click work. There is work going on to bring a proper multitouch api to xorg, so gestures can be used correctly.

I've played around with multitouch on Ubuntu, it does work with some hardware (but not if the driver intercepts the touches and synthesizes something like scrollwheel events, that's bad).

See eg. https://wiki.ubuntu.com/Multitouch and https://lists.launchpad.net/multi-touch-dev/msg00997.html

I have full multitouch on this laptop, and use the two-finger scrolling and triple click that is provided by the synaptic driver everyday. The inability for programs to directly use gestures isn't great though.

This. The trackpad is godly. I haven't seen a PC equivalent.

Assuming you mean desktop and not laptop PC, there's this: http://www.apple.com/magictrackpad/