A few years back, the local London Drugs was selling (for about $3,000) a SONY UX micro PC. I dismissed that as both overly expensive and impractical.
But more recently, in the local public library, which is also a free WiFi hotspot, I saw a young woman of Korean extraction using an (early) Everun Note. At the time, I was astonished at the compactness of the item. There are other UMPCs, but they're not normally sold in North America; there's IBM's PC 110, and there are the machines by Kohjinsha (actually by Inventec, and I see they're going to sell them under the Onkyo brand in future...).
The trouble, of course, is that in the North American market, people value computers for their power and features - and are not prepared to pay a high premium for portability.