Love caniuse.com but unfortunately there's lot missing from this support matrix.

More important than which browsers support the API is which underlying protocol version the sockets speak. A lot of major browsers support the API but very few speak the same protocol.

I believe today's announcement is a finalized protocol standard which means that there's finally going to be a lingua franca for websockets.

I let socket.io worry about that. Great library.

I agree about socket.io. It works quiet well for most of what I need. The only issue I have with is is I can't figure out if it now supports sending and receiving ArrayBuffers? Does anyone know anything about this?

My use case involves sending model data to display in WebGL. Sending it any other way would be inefficient.

It's something we're currently working on. We're going to be integrating a XHR binary data fallback as well into our realtime engine.

socket.io is a great library, agreed. However, a nice thing about standards is you can program to the specification and provide support on other platforms. Working on a project that involves node, a browser client, and a couple of mobile platforms -- socket.io is great for the server->browser websocket or comet case, but for the mobile case investigating the proper library (or hand rolling a compatible WS/comet implementation) is needed.

The step towards standardization will make this type of cross "platform" compatibility easier in the long run.