This whole home automation space is crazy. It is fractured into many many different and incompatible “standards”. I have heard (though not verified myself) that many of the Zigbee radios used for home automation are not compatible and there are cases where the central hub has multiple radios to deal with the differences in the networking stacks. Other physical standards like wifi have standard physical layers (802.11), standard network layers (TCP/IP) but lack standardization higher up in the application layer.
So, Zwave. There are literally 100’s of compatible devices. And, as best I can tell, most anything that you would want or need to do home automation. I personally think that it is really cool that I can buy Zwave devices at Lowes in Georgetown, Kentucky. You can buy them at Amazon, Staples and many other online places. That is pretty awesome as well. Zwave also seems to be one of the least expensive radio standards, you can buy modules in low quantities from Digikey for $5. The least expensive wifi modules are something like $15 in low volume.
But it is really annoying that Sigma trys to squash the low volume market by raping their would be customers for development kits and software licenses.
On the hub/host side of Zwave there is OpenZwave, an open source project to provide host side control of Zwave networks. The groups seems to be pretty active and I think that I will try out some of their stuff.