I've had some experience with Instant Messenger. A few years ago I used Yahoo Messenger to keep in touch with family on occassion but after a while I started getting inappropriate messages from strangers and that soured me on the whole thing.
Setting up the AOL Express account went smoothly. I found three co-workers online and started messaging them right away. I found that trying to carry on three conversations at once was a bit much :) but it was a fun experience.
I don't really see this replacing other means of communication at work. A phone call or an email works just as well. Plus I go back and forth from my desk to the stacks to the front desk so much that if someone were expecting an immediate response through IM they might be disappointed.
