Evaluations of the Sheevaplug in particular revealed it tended to
overheat badly if you put any significant load on the networking
components. Heating problems combined with poor quality control would
be my guess as to why that whole thing never flew.

I also understand some of these other thingies have heating problems too, but that they're being addressed and believe at least in the just sent out batch of MK802's (I said second generation in the other message, that's probably not a fair characterization) it is supposed to be either fixed or at least alleviated.