I have been slightly involved (through Jisc funding) with the ResourceSync specification project, being led by Herbert Van de Sompel of the Los Alamos National Laboratory. The project has just released a draft specification, which is available at http://www.openarchives.org/rs/.
The draft will be available for public comment until March 15th 2013 - you are invited to comment via the ResourceSync Google Group. Group discussions are openly accessible; posting requires group membership.
In Herbert's words:
The ResourceSync specification describes a synchronisation framework for the web that consists of various capabilities that allow third party systems to remain synchronised with a server's evolving resources. The capabilities may be combined in a modular manner to meet local or community requirements. The specification also describes how a server can advertise the synchronisation capabilities it supports and how third party systems can discover this information. The document formats used in the synchronisation framework are based on the widely adopted Sitemap protocol.
ResourceSync is a collaboration between the National Information Standardization Organization (NISO) and the Open Archives Initiative (OAI). It is funded by the Alfred P. Sloan Foundation and Jisc.