When the Java Content Repository (JCR) standard first came out it was supposed to bring in a new era of compatibility between content repositories and put an end to the content silo. There was, and still is, a lot of talk about it and just about everyone added JCR compliance to their marketing materials. Unfortunately, that’s mostly where things stopped - the implementation work that followed was generally done was buggy or incomplete and the only viable JCR implementations that I’ve seen have come out of Day Software, who lead the JCR spec effort.
I’ve always wondered why Roy Fielding, of all people, would say something like this:
I expect JCR to become the central interface between Java application development and future content management infrastructure, just as HTTP/1.1 has become the interface through which everyone uses the World Wide Web.