US CMS, SDSS, and iVDGL have sponsored an effort at Fermilab, the VOX Project (VO Management Service eXtension), to investigate and implement the requirements, both policy-related and technical, for admitting collaborators into a VO, and facilitating and monitoring their authorization to access the available grid resources.
The newest version of VOMRS (v1.3.3a) was released on May 1st, 2009.