From Moteiv’s blog:
The Mobile & Embedded System research group at Yonsei University has released a new operating system for wireless sensors networks called “RETOS”, Resilient, Extensible, and Threaded OS for Wireless Sensor Networks. Information about the operating system was published at this year’s IPSN/SPOTS conference, where I was a member of the program committee. The initial release supports Moteiv’s Tmote Sky modules.
RETOS is a departure from the standard TinyOS framework that many know and love. It supports dynamically loadable modules (ala SOS from UCLA) and a multithreaded system allowing programmers to block on events instead of building complex state machines for asynchronous code.