WebSocket "TCP for the Web," is a next-gen full-duplex communication technology for web apps being standardized as a part of Web Applications 1.0. WebSocket protocol is more efficient than HTTP as used in Ajax, so it's more suitable for real time & dynamic web apps.
"WebSocket specification has now been updated to draft-ietf-hybi-thewebsocketprotocol-00. This version relaxes requirements on handshake messages to make it easier to implement with HTTP libraries, and introduces nonce-based challenge-response to protect from cross protocol attacks. These changes make it incompatible with draft-hixie-thewebsocketprotocol-75; a client implementation of -75 can't talk with a server implementation of -76, and vice versa," revealed Google.