Sun SPOT should be rolled out in May – looking forward to getting my hands on these. Here is an intro for information:

Based on a 32 bit ARM CPU and an 11 channel 2.4GHz radio, Sun SPOT radically simplifies the process of developing wireless sensor and transducer applications. The platform enables developers to build wireless transducer applications in Java using a sensor board for I/O, an 802.15.4 radio for wireless communication, and use familiar Integrated Development Environments (IDEs), such as NetBeans to write code.

The Sun SPOT system features the “Squawk VM,” a small J2ME virtual machine (VM) written almost entirely in Java. It provides the ability to run wireless transducer applications “on the metal,” (directly on the CPU without any underlying OS), saving overhead and improving performance. End users also gain the flexibility to experiment with different implementations of low-level services, such as networking protocols, which are typically buried inside an OS. A set of Java libraries under development will provide access to the sensors, the I/O pins on the sensor application board, and the integrated on-board radio. By running multiple applications on the one virtual machine, and by using a more compact representation of class files, the Squawk VM makes better use of the small memory space available on SPOT devices.