I'm trying to build a chatroom in the conventional sense to operate in the browser but with a decent API layer allowing for decent abstraction between the server and the client.
I want to keep it SIMPLE, but still have room to develop extra functionality going forwards, such as saving transcripts in the database.
You can use faye.
https://github.com/jcoglan/faye
There is also a Railscast for this http://railscasts.com/episodes/260-messaging-with-faye