I recently gave a my Realtime Web Apps in the Wild talk at Fluent Conference in San Francisco. It's a pretty big event with some impressive and well-informed speakers, so it was great to be part of.
The slides also contain links to the demo videos for the appropriate slides, identified by this image:
Remember to check out the cool Ghosts demo.
If you are interested in this realtime technology then why not sign up for a free Pusher account and add some realtime functionality to your web or mobile application.
I was asked some information about HTTP v WebSocket latency so here are some graphs from some a CometD benchmarks blog post demonstrate latency comparisons.
I also came across this video which visually demonstrates the latency using a demo.