touch screen is great for mobile devices
(E-Book readers, music players, satellite navigation, et al)

but I don't see it taking off on the desktop
(keyboard & mouse is quicker for most things, plus people's arms get tired very easily)

Remember, touch screens aren't new
they've been tried before - and apart from hand-held devices, pretty much bombed

It's the multi-pointer GUI framework that's new (both for windows & *nix - see here http://lwn.net/Articles/283957/)

I see multi-pointer systems taking off in areas where side-by-side collaboration is needed - particularly schools

but I don't think touch screens will gain much traction on the desktop