I believe that the gateway, the “sensehub”, has a lower BOM cost than Nanode or any other open source wireless gateways and has more flexibility due to the CC1100-style radio.
The firmware provides a low power radio link from multiple sensors to the gateway. The gateway proxies to Pachube for recording data and providing a shared key/value database between nodes.
There’s an Arduino-sketch like language or you can just use the C APIs.
There’s a serial bootloader, OS-library and sample apps. The gateway uses the uIP TCP/IP stack.
Via the forum.