At Bump we tried Campfire, but ended up using IRC (and use an open source IRC bot, https://bitbucket.org/yougov/pmxbot/src). I'm curious why you decided to go with Campfire instead of IRC.
We depend on having a nice, customizable native Campfire client. We keep a custom js script in DropBox that Propane (http://propaneapp.com/) loads on startup. We've been able to modify the UI to show avatars, highlight successful/failed builds in Git push notifications, etc.
CF also gives us a few other nice features, like offline transcripts with search, and STARS.
Surely, you can do all this with IRC... and there are other chat apps that people like too. We're hoping that people add support for them to Hubot.
https://github.com/github/hubot/blob/master/src/hubot/irc.co...
It has some web-oriented features like auto-linkification, condensing long responses, embedding of images, tweets, videos...
It's better to think of Campfire as a client than a protocol; there's nothing it doesn't do that a sufficiently advanced IRC client + logging bot combo can't replicate. I prefer the latter, myself, but I can see the value it adds for many.