This question has been answered: Do websockets allow for p2p (browser to browser) communication?
The answer is no.
My question is: are there any plans for this? Any speculative draft by the W3C or whoever, planning this capability? (I have googled and found nothing, but I'm not sure if I'm searching the wrong thing.)
There is the WebSockets API, which allows you to, for example, transfer files from one user to another quite efficiently (like http://jetbytes.com/ and some others I've seen). I believe these work by piping the file through the server - it's very light on the server, as it doesn't have to store each chunk after its sent to the receiving client. But it does use the server's bandwidth twice (down and up) for each file transfer.
It would be more efficient (for server and both clients) if the server could just pass the IP address (and a port?) of each client to the other, and the entire data transfer could take place between them.
For security, the browser could prompt each user to give permission ("This website, example.com, wants to connect you to IP address 1.2.3.4 to receive a file transfer of 23MB. Allow/Refuse?").
If there are no plans to publish a spec on this, why not?