From Sun’s SPOT (Small Programmable Object Technology) webpage:
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.
This Summer, a development kit will be available that includes two complete Sun SPOT devices with demo sensor boards, a base station Sun SPOT to connect to your development machine, and all the software development tools and cables required to start developing applications for your Sun SPOT. The projected introductory price is $499.
Be sure to visit the forums to join other developers in the Sun SPOT community.