I had just started on this very task;
I have Rako gear in my house, and have just finished a project based on a mesh network of XBee (Zigbee protocol) modems, connected to Arduinos, to control my central heating. The core of this is a small Publish/Subscribe engine, which I can access over the web, or using my iPhone. (JSON interface to the hub). The Rako kit is my next target.
I contacted Rako, but was told they would not publish any API, so you fared better there.
If there is anything I can do to assist, please let me know. I will certainly be beta-testing for you!