WebSocket features will likely be introduced first for HTML 5 development with BridgeIt rather than JSF development with ICEfaces. (Where we can introduce new APIs outside the JSF request/response model.)
Do you have an application that would benefit specifically from WebSocket? The main advantage with the HTTP strategy with ICEpush is that it has the widest browser and network infrastructure support (some firewalls will block WebSocket). Since the PushRenderer API would remain the same, there would be little visible difference to the application developer.