Looks like Websockets are supported. I recently tried to log into our SA UI and it errored out (some bug) but was was spit out was some XML around the use of Atmosphere Web Framework which is indeed what is used to provide Websocket support for the REST API.
Now I just need to figure out how to make use of this... I am trying to write client-side Javascript to maintain a persistence connection to various decoders/concentrators/brokers etc.. and publish/monitor statistics.
