Sun Labs have developed a cute little Java-programmable board called the Sun SPOT (Small Programmable Object Technology), along the lines of the Berkeley Motes project and other small Ubiquitous Computing sensor boards:
Based on a 32 bit ARM-7 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 Net-Beans™ to write code.
The system uses the IEEE 802.15.4 wireless standard that’s designed for short-range (< 10 meters, same as Bluetooth) with low data rates but also low latency and ultra-low power consumption — pretty much what you need for individual sensors.