The nerves foundation is usable today.
Once the Nerves SDK has been installed, you can start your own Erlang projects and build them in the Nerves environment. Look at the demonstration project for a simple example. The Getting Started screencast below walks through the SDK installation and the demo application build step by step.
The mailing list is the best place to go for any questions. If you'd like to contribute bug fixes or new features, please go ahead and fork the project and send me a pull request.