ZeroMQ - Distributed Computing Made Simple 

 * The socket library that acts as a concurrency framework.
 * Carries messages across inproc, IPC, TCP, and multicast.
 * Connect N-to-N via fanout, pubsub, pipeline, request-reply.
 * Asynch I/O for scalable multicore message-passing apps.

Version 4 Features:

 * New wire level protocol, ZMTP/3.0
 * New security framework with PLAIN and CURVE mechanisms
 * New ZMQ_STREAM socket type

WWW: http://www.zeromq.org/