Signal to noise ratio is a pet peeve of mine (I'm sure I'm not the only one)

Interestingly, I find IM to be the most distracting form of communication (I also believe that email is becoming a form of IM). As you say, people use IM to reconnect, however it carries an expectation of immediate response without the consequence of being considered interupting. I can be deep in the zone with obvious visual queues that I'm concentrating really hard, only to have the remote staff send me IMs and get really annoyed when I don't respond immediately.

More conversation would be immensely useful: people are often spartan with the information they provide in "quick notes" over IM. I would favour less frequent, but higher quality communication.