Use Campfire? Check out Pyro
Campfire is the web-based chat application by the folks at 37 Signals. It's full of Web 2.0 bells and whistles, and looks like a good means of cross-platform, application independent collaboration. Earlier this week, 37 Signals released the initial beta of Pyro for Campfire users who have Macs. They're calling it a "site-specific browser," in that its primary purpose in life is to interact with Campfire.* Enhancements Pyro offers include:
A single location for all your chats
Chat room/message status in the dock
Access all open rooms in a single window
Pyro is universal, free and requires a Campfire account (obviously). No specific OS requirements were given.
*No, the irony of using Mac OS-only application to interact with an application independent, cross platform chat system is not lost on us.