Firefox 4 ditched WebSockets for security reasons. Does anybody know the justification to add it back now? More specifically, do they fix the security issue of WebSocket, or do they just give up to the popular demand?
In the new protocol, Websockets traffic is (trivially) encoded so that it (a) can't accidentally be interpreted by either endpoint as something other than Websockets and (b) can't confuse middleboxes.
Basically, "new" Websockets has custom Websockets encryption that nothing other than Websockets will be speaking, so, if you're talking Websockets, it's because both endpoints consented to do so.
http://w2spconf.com/2011/papers/websocket.pdf
(Full disclosure: I'm a co-author of that paper.)