RSS is an acronym for either RDF Site Summary, or Rich Site Summary or Really Simple Syndication. All of these actually are different names for the same technology. RSS is an XML format for distributing syndicated content such as news. It can be applied in libraries and actually there is a growing literature about application of RSS in the libraries. For a simple and non-technical introduction to RSS you can read this article by Steven M. Cohen on LLRX.com website.