I’ve been off instant messaging for years. There was nothing about it that I found appealing or that added to my productivity.
I realized this morning that Twitter has become my new IM. I publish what I’m doing (and as a result people know if they can reach me or not, whether to try me at my office or on my cell, etc.). I stay in touch with my friends and colleagues by following what they are up to (and therefore know how to get in touch with them if I need to). Through following and being followed I keep up with more people and don’t have to "check in" as much because I know what they are doing, where they are traveling and who they are spending time with. And of course through Twitter’s direct message feature, I’ve literally replaced IM by enabling people to get in touch with me directly and quickly (and I pay way more attention to a Twitter DM than I ever did to IMs; they also show up on all of my computing devices so they are more likely to find me that IM, which seemed to route messages randomly among my various IM clients and whatever machines I had that happened to be "online" at the time).
Nicely done, Twitter. Nicely done.