The WebSocket protocol has been standardized by the IETF and the WebSocket API is almost standardized by the W3C. A number of Java implementations have become available including servlet containers like Jetty and Tomcat. The Servlet 3.1 spec JSR-340 will likely define the initial WebSocket upgrade request while JSR-356 will define a Java-based WebSocket API.
WebSockets results in a messaging-style architecture, in contrast to a REST-based HTTP architecture, and is arguably much more usable with some additional protocol like XMPP, AMQP, STOMP, etc. There are plans to support it in Spring Integration but there is also room for such support in web applications, support on which Spring Integration could potentially build upon.
If you'd like to see such support added please comment on specific uses cases (or experiences) and requirements for using the WebSocket protocol in a web application. Keep in mind the WebSocket protocol is full duplex and support should be usable on both the client and the server side.