>true if only one-shot get/post are exchanged. Having cookie-like validation embedded in the payload would make it easier for REST/Ajax/Soap-style enhancements and lessen the pain of rewriting URLs and the ease serverside other stuff mentioned in thumbs down. The URL-mangling smells like premature optimization to me, unless you find some measurements citing massive gains.

The only see I could see right now is to bypass the browser setting of the cookie and benefit of recognition support, for example. But, I will have to take a look at HTML 5, as mentioned earlier on, to see how this is implemented.