I don't have IM set up at all, for the same reason that I've never tried crack. I've seen what it has done to some friend so of mine, so.........
I know what you mean. I rarely sign on to AIM any more, thanks to a few friends who ambush me at the worst times. Ya just gotta be able to say, "sorry, gotta go." Unfortunately, one of the groups I work with uses YIM for work communication, so I gotta stay connected there while I'm at the office. (Luckily the aforementioned friends haven't figured that out yet.)
However, I have no use for the people in restaurants and bars who are madly IM'ing on their PDAs about god knows what. My god, man, just be in the moment. Whoever's on the other end can live without your deathless prose for a few hours. </ rant>