@aburka identi.ca as of July 2013 runs the pump.io protocol.

The standardized ActivityPub ("AP") protocol the Fediverse of today runs on was based on the pump.io protocol, but is not compatible. For starters pump.io uses ActivityStreams 1 but AP uses ActivityStreams 2, which was developed alongside AP.

Here's hoping that one day pump.io will implement ActivityPub and identi.ca will join the Fediverse once again!

@evan