As I was checking Nokia Conversations today, I saw that their video of the day was titled 'Multitouch surface with N95 as a webcam'. Intrigued, I clicked through to the YouTube video.
As you can see in the above video, it's possible with the help of Mobiola Webcam to use your N95 or other camera equipped S60 device as the webcam needed for the home-made Multi-touch pad.
I'm planning to create a set up like this but instead of using the USB, I'll be using bluetooth to create a wireless touchpad. I'll post a video up here when I'm done, stay tuned!
Instructions for the build can be found here.