My team uses Slack (http://slack.com http://slack.com) and is very happy with it. It's in active development, and has good cross-platform clients. (Flint for

My team uses Slack (http://slack.com http://slack.com) and is very happy with it. It's in active development, and has good cross-platform clients. (Flint for Campfire is great, but last time I asked they didn't have any way to do volume licensing)