Steve "Chippy" Paine, formerly of British Telecom but now of the UMPC Portal, has published a free 33-page Ultra Mobile Computing Buyers Guide (PDF). It doesn't review the hundreds of different products, but it does provide a concise overview of the various types of device and the main chips, screens, storage systems, operating systems and other technologies involved. It's a useful read if you are thinking about this sort of device.

If you follow the site, yes, it has been published there as a four-part series….