give a chance to Faye server is very stable and
nice, but their api is not like websockets api.

Faye looks quite interesting, but it's a different beast than SockJS. First, the underlying Bayeux protocol is ajax-based - it's from pre-websockets era. Second, the protocol does have a publish/subscribe semantics, while the point of SockJS is to do transport layer only.

It’s a bit funny to see another useless Node.JS library in RabbitMQ’s blog. There is no reason to do it with Node.JS instead of Erlang other than do it fast and dirty.

Here you are: "fast and dirty"! We do plan to do a stable Erlang SockJS server soon. And yes, prototyping in Node is simpler than in Erlang IMO.

And I can’t see how it is related to RabbitMQ, which doesn’t have good enough WS interface yet.

WebSocket is a transport. RabbitMQ is all about semantics (AMQP is both). We could easily create a websocket plugin, but what exactly would you send over it? Also, Rabbit semantics don't really fit in the web context. But we did few experiments in that direction, for example take a look at rabbit-socks, which allows you to speak to RabbitMQ using STOMP over websockets.