Lets re-invent the computer interaction metaphor: what would you like to replace the desktop?
Personally I'm partial to the vending machine metaphor Apple is now leaning towards. I'm a fan of the idea behind a spring board, but I think that even iOS hasn't removed itself enough from the "desktop" years. If i had to pick one now, it would be the "deck of cards" user interface/metaphor. I think it fits the touchscreen era we're in the best, and I would have loved to see it applied to a large screen device with powerful hardware.
How about you?
But that too begs the question, "What about on the actual desktop?" I guess the mouse could be replaced by some sort of large trackpad, again - Apple style, with the mouse assuming a role more akin to a graphics tablet or joystick - becoming a peripheral in the truest sense of the word.
Lately I've been using Unified Remote on my Galaxy Nexus to control my laptop (an HP DM3) while it was connected to the TV and the experience was more or less quite smooth. This could be an area where Microsoft and Apple could expand, improving the inter-operability of their devices between mobile and desktop tech. Google should do the same for Google TV and create apps that does just what I've been describing for Mac OS and Windows.
Actually, I quite like where this is heading.