Sun has been licensing and promoting Java in embedded applications forever, which is not totally surprising since Java (nee Oak) was invented for "connected devices" -- set-top boxes and the like. And of course there's J2ME, which you'll think is either a brilliant success or an industry-plaguing disaster, depending on whether you've ever needed broadly to deploy an app on the platform.
At the MakerFaire, they were showing off "Project Sun Spot," a sophisticated experimental gadget with a 180MHz processor and radio networking. The most interesting attribute of the Sun Spot, though, is the integrated accelerometer. With a little room and a sensitive enough accelerometer (actually you'll need to slave a couple of them) you can build all manner of fun and dangerous things. Like inertial guidance systems.
Never mind that a 180MHz device ought to be able to run full-on Java (Sun seems to have realized this, acquiring defunct SavaJe and leveraging their J2SE tech toward JavaFX mobile). Something getting shot on rockets for experimentation oughtn't to cost $550 + shipping!
Happily, you can buy these 3D accelerometers for $35 and bring your own ... everything else: