Suprised no one has yet brought up the obvious comparison to campfirenow.com and hipchat.com. While being free and self host-able is nice, the Candy UI seems light years behind its for pay competitors.

But I'm glad to see more options available. I've been advocating web-based chat in my offices for quite a while now, and am happy that a few decent choices have finally started to pop up in the past couple years.