Meta Directory

directory of directories? esp of Digital Identity?

Message Bus? not quite

So, what is a metadirectory? It's software that goes beyond directory synchronization to enable a single view and administration of multiple directories--so that changes can be made from the top down, the bottom up and peer-to-peer. While metadirectory software will initially have its greatest appeal to those who administer multiple directories-- particularly in the more traditional e-mail sector, Kim Cameron's vision for it is much more expansive. "We have to completely change the way we look at a directory," he says. Although directories are the domain of administrators today, he sees that responsibility shifting to end users in the future. In fact, he believes the metadirectory will prove to be the grid on which the Internet will be organized. Enterprise Address Book...

http://en.wikipedia.org/wiki/Metadirectory

LDAP?