I just read about overheating and stuff - I cannot copy that. It runs smooth, hand-warm, with the ethernet cable connected all the time it's being powered on.
So perhaps I received one with an already fixed power supply?! ... Whatever ...
Hmm is your hand hand-warm at the normal human temperature between 35,8 and 37,2 °C (96,5 to 99 °F)?
Then my GuruPlug is also hand-warm...but with this temperature 10 °C warmer as my SheevaPlug....
My GuruPlug Plus runs now after some days from 35 to 39 °C with one Conenction at eth0 and WLAN enabled.