WebRFB is a rewrite of the RFB protocol specification, based on top of HTTP rather than TCP. The motivation for this rewrite is described in the specification.
WebVNC is a reference implementation of WebRFB. It consists of a JavaScript client written with GWT, and a Java server that can either provide direct access to the server's desktop, or can act as a proxy or reflector to another WebVNC (WebRFB), VNC (RFB), or RDP server.
Both are currently in very early stages of development. See our project page for the latest status.
If you are interested in helping out, send a message to one of our mailing lists:
webvnc-users (for bug reports, support, and general discussion) webvnc-devel (for development discussion) webvnc-protocol (for discussion related to the WebRFB protocol)
There are a number of similar projects that you may want to check out if WebVNC does not meet your specific needs: