No touchscreens for desktop computers. It's just silly!
Interesting to see all the comments along the lines of 'this won't work'. (Such people whined when Jobs took away their floppy drives, too.) Actually, it's brilliant. Apple needs to work out some ergonomic issues, but essentially, Apple sees the keyboard and mouse as legacies of a now-bygone age.
Your keyboard is arranged in the 'QWERTY' style to keep non-existent striker keys from being entangled. And the mouse was a solution forced upon us because touchscreens were strictly science-fiction.
Apple sees the acceptance of the new user-interface paradigm it has pioneered and is now seeking a way to bring that to mainstream computers. It's a gutsy move. If Apple can make it fly, mouse and keyboard users will look like dinosaurs.
Unlike the floppy, I don't think mice and keyboards will vanish. Heavy users (especially the sort that needs Mac Pros) will continue to find utility in them. But their use will differentiate the Heavy Computer User from the lighter user who has a different approach and different needs. They'll embrace this sort of device - but only if Apple does its homework and really implements this thing properly.
Most people, I suppose, think there'll always be a keyboard and mouse because there has always BEEN a keyboard and mouse. But things are evolving, and Apple gets it. They've seen the computers in films like Minority Report, where there's not a keyboard in sight. They've seen how people have embraced the keyboardless, mouseless iPad. They know which way the wind is blowing.