I own the GuruPlug Server Plus, and have had nothing but problems with it. It stopped acting as a wireless access point, so I had to buy the JTAG hardware to be able to get into the device and fix things.
Once I had things up and running, I found I can only transfer data wirelesses so long before it loses its wireless connection, and seems to have some data transfer errors. If I’m not transferring a lot of data, the wireless connection seems to be stable.
And it gets hot.
“GuruPlug Server Plus : don’t waste your money on it!” is a good overview of why to avoid this product.
“GuruPlug Server Plus Heat Problems” includes photos of various “solutions” of taking the device apart and bulking it up with a fan or heat sinks.
I’ve also read about problems with the SheevaPlug (GuruPlug’s predecessor) and its power supply.
Plug computers sound like a great idea, but the GuruPlug (and its 30 day warranty) are one to avoid.