I got three (I wanted one, boss ordered three, sigh!) of these to develop on a "ARM", when Tonido did not have enough in stock.
These sound like a small turbine. It is impossible to work with these switched on.
The earlier versions were heating up so badly and melting electronics, that the manufacturer decided to put a crappy fan inside and create a new problem.
Get the JTAG/UART device, it will save your ass when you render the poor thing unbootable with a kernel replacement. There appears to be a network boot attempt in the power up, but I haven't seen documentation for it.
One caveat: The wifi range is ok, but not top notch, and when running as an access point it can only support 8 devices, which isn't much when people show up with a phone-ipad-laptop bag.
I also have a SheevaPlug installed in an uncooled building that regularly exceeds 100F in the summers, and it seems to be doing fine after replacing the crappy original PSU with their updated version.