The box I'm holding is actually a TonidoPlug with a SchoolTool sticker on it. The TonidoPlug is, in turn, just a generic SheevaPlug. Buying a TonidoPlug seems like the easiest way to play with plug computing in general. Specific to the TonidoPlug is some... other software which I really haven't tried to figure out yet, aside from noting that it does some useful dynamic dns stuff out of the box which helps you locate the server both inside and outside your home network.
So, what is this thing?
OK, take a wall-wart power supply, more or less double it in size, stuff the processing guts of a smartphone in there, add an ethernet jack and USB port, and install Ubuntu 9.04 server. It's a Linux server with a 1.2 gigahertz processor and 512 MB RAM and flash storage. All solid state, add whatever mass storage you want via USB.
It is not i386 PC architecture though, it is ARM, so you need binaries compiled for ARM, and you can't just install Linux from a generic CD image.
To build and run SchoolTool from source on a USB key, I just followed the standard developer instructions. We'll be able to build regular Ubuntu .deb packages in the future as well.
SchoolTool runs roughly as third as fast on the TonidoPlug as it does on my (oldish) PC. This would primarily be aimed at small schools in the developing world, who would not be bombarding the server with lots of simultaneous requests, so once we clean up a few existing performance problems on specific views (which go from annoying to unusable on this processor), it should be fine.
This provides a number of interesting possibilities for distributing plug and play SchoolTool appliances, and I'm looking forward to figuring out how to make that happen, whether via local vendors, government ministries, or some other route. Right now I'd say "Coming in 2011."