Glad you think it's cool, we are pretty excited.

Authentication and access control are features which are very important, and we are working on a couple of options for doing it. Something similar to what you have described is the current favourite, though the hashing probably won't be passed through at channel level.

We decided to get the Pusher launched into beta with stuff like this left out so that we could get a gauge for people's general enthusiasm for such a service.

We'll be busy in the next couple of weeks reacting to feedback, so it is great to have these kind of comments :)