OpenMicroBlogging is an open protocol that allows different microblogging services to inter-operate. It lets the user of one service subscribe to notices by a user of another service. This enables a federation of new communities, as potentially an organization of any size can host a service. OpenMicroBlogging utilizes the OAuth and Yadis protocols and does not depend on any central authority.
OpenMicroBlogging has been superseded by an enhanced version of it, OStatus. OStatus will also be implemented by the Diaspora social platform.
History
The first implementation of the OpenMicroBlogging protocol is the Laconica software, which changed name to StatusNet in August 2009. Identi.ca is the first service to support OpenMicroBlogging, and other sizeable services including Leo Laporte's Twit Army at http://army.twit.tv are amongst those powered by the open source StatusNet.
Since March 2009 one can search users' accounts in Twit Army from within Identi.ca. You also can subscribe to accounts at Twit Army from your Identi.ca account.
The second implementation of the OpenMicroBlogging protocol is the OpenMicroBlogger software.