projects:gpgAuth
FireGPG (http://www.getfiregpg.org/) used to provide the gpgAuth client functions as a module - since FireGPG has been discontinued, the available versions are outdated and do not work with the latest version of gpgAuth.
I am currently working on a separate and standalone extension for Firefox that will implement the new gpgAuth NPAPI cross-platform multi-platform plugin.
I estimate by mid February 2011 I should have a stable Firefox extension for Windows, Linux and Mac.