Re:gaim works for me, but loses ground from here (Score 1)

I've used IM in every company I've worked for in the past five years. Private offices combined with ubiquitous IM usage gives you the best of both worlds -- you get the highly collaborative environment like when you have your whole team in a room and, when you want privacy, you just set your IM to "busy."

As mentioned above, it also allows you to extend your collaborative environment to everyone you've ever worked with -- you have the resources of your entire career and you become a resource for that much larger group.