Running in a browser is great for getting started, but anyone who's a web developer will have their browser tank and take down every web-based app with it. For this reason it's always nice to have a native client option. Propane (http://propaneapp.com/) is great example of a simple native client.

Secondly, please, please bundle in XMPP so that writing agents for this kind of app isn't an exercise in sheer frustration.