Lorien OS
Lorien is an advanced operating environment for Wireless Sensor Networks providing unparalleled modularity and dynamic systems support. Lorien components can be individually added to and removed from sensor nodes while the system remains online with complete system integrity and strong type safety. Lorien also includes the Wisebed OS Abstraction layer allowing Lorien application components to execute unmodified on a range of platforms including the Shawn simulator.
Documentation, forums and source code are available at http://lorienos.sf.net