Last week, Sigma Designs made significant parts the Z-Wave specification open the the public. This includes its device classes, command classes and security protocol. Prior to that, developers had to sign an NDA and purchase a development kit in order to make use of Z-Wave in any significant way.
This is great news for Hobson. I developed the WZWave library that Hobson uses without access to official Z-Wave documentation and instead relied on work done by the OpenZWave project and other miscellaneous resources found on the Internet. With the official documentation, a lot of questions can be answered and the WZWave library vastly improved. I'm actively in the process of bringing WZWave into alignment with the official documentation and introducing support for secure devices.
One piece of documentation notably absent from the public specification is the serial protocol used to control Z-Wave PC controllers (e.g. USB sticks). I still have quite a few unanswered behavioral questions in that area so I'm hopeful that additional documentation will be released. If not, Sigma Designs says they are setting up a community forum to answer Z-Wave questions which may be helpful.