WebSockets is a web technology providing full-duplex communications channels over a single TCP connection. The WebSocket API is being standardized by the W3C, and the WebSocket protocol has been standardized by the IETF as RFC 6455. Apache, among others, are developing WebSocket technology. The HLL WebSocket server (High Level Logic (HLL) Project) was one of the first (if not the first) to work and offer a live demonstration (with downloadable browser code) conformant with the final version of the WebSocket standard.
The idea of using WebSockets in web app projects along with servers like Tomcat is getting hot. I'm just putting in my two cents worth, related to the HLL project, on my blog. HLL is a software framework for intelligent distributed systems. The WebSocket standard was a very welcome addition and I'm obviously an enthusiast. The day is fast approaching when browsers will become serious application interface technology. HLL can help make your slice of the Internet "the application". (Paraphrasing Bill Gates in perhaps a bit of an obscure way.)