I think the biggest obstacle we've got at the moment isn't price, or size, or cpu power. All these have been shown feasible (mostly) with the UMPC type platforms. The problem we've got is battery life. There have been a lot of press releases about "breakthroughs" in battery performance in the last 6-12 months, most of them talking about some kind of nano-tech. If any of these come to fruition then we're a BIG step closer to the dream. Tech like this is just going to make portable devices more practical.

And with the Antelope-type platforms, they're nice but I'd rather have the display permanently attached. Why plug the "core" into a screen? The device could automatically disable the in-built screen and upscale to a higher resolution; just like a laptop in a docking station.