I am still not planning on continuing development on the WordPress Users plugin. However, rather than kill it entirely or let it linger in the WordPress Plugin repository, I thought that it might be better served to move the codebase to GitHub. I hope that putting the project on GitHub will bring more visibility to it so that others may be encouraged to contribute to the development of the plugin.
Make sure to get the latest version from GitHub instead of the official WordPress Plugin site. If you are using it and have a problem or a question, please create an issue there. If you want to contribute, please submit a pull request. I will try to help out where I can so that others my still find it useful.