The FLEXOR is a software architecture that is designed to support the testing and management of WSN protocols and applications in a flexible way. Its main goal is to provide run-time support to experiments on backchannel-free sensor networks.
As of Jan 2009, this project and NanoStack 1.x are no longer being actively developed or maintained. Instead there is an effort to add support for Sensinode/cc2430 hardware for the Contiki OS. http://www.sics.se/contiki/