It’s just a concept at this stage, but Clayton Miller’s 10/GUI project is getting people’s attention. It proposes a way multi-touch might work in the desktop scenario – detached from the screen, like a giant trackpad, or tablet.
It’s hard to see it working perfectly, or being as universally applicable as the trusty mouse, but there’s certainly some good ideas there, some I’m sure we’ll see one way or another in years to come.