The CMIS standard provides a vendor-neutral interface to content repositories.  CMIS is well-supported by the likes of IBM, Alfresco, Nuxeo and Microsoft, among others.  While the server side is important, a good set of client libraries will make it easier to take advantage of the new interface.

Enter Apache Chemistry.  Chemistry is a set of client and server libraries for applications written in Java, PHP, Python and now, .Net.  Chemistry was in the Apache Incubator for a while but has now officially graduated to a top-level Apache project.  Congrats to the project team and their continued success!