A few weeks ago someone asked if anyone knew anything about the tiny little Gumstix PXA255 systems:
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I treated myself to one for Xmas, and it turned up this morning. I should have got it on Xmas eve but I was out when UPS tried to deliver it. Haven't tried it yet, but it is incredibly small and a lot of nice things have been said about in other forums. The design has been revised and it now has a lot more I/O lines, which was one of the shortcomings that people have complained about.
Leon