OpenForge is an API (Application Programming Interface) that allows different development forges to communicate each others. All the work is focused on interoperability.
(From OpenForge.info)
OpenForge is a new data exchange format that is slowly being introduced into ShareSource. It’s not really production-ready just yet, but it will be there by the end of this year.
See the site, with the lastest draft specification at OpenForge.info