I hate it when people assume that if you're online and they send you an instance message, then you have to respond.
The problem I find with IM, and many Web 2.0 software like Facebook and MySpace, is that it puts the power in the person querying for information, and not in the person providing the information. (or in the IM world, the power is in the person initiating the conversation, and not the person accepting the conversation).
This construct has fostered a culture where if you don't respond to an IM, or if you don't add a person as a friend, then that person feels that they are being ignored and you look like a jackass.
So what do I do? I want to use Facebook, but I don't want to accept every friend invitation sent to me. (And FYI folks - there is a reason why we lost touch). I also want to use MSN, but I have work to do and can't chat on every message - not to mention that damn flashing window is such a distraction.
I think I'm going to uninstall my MSN at work. The distractions are significant enough where it has affected what I was doing at the time, but I feel that it is also changing work culture to the point where people think that MSN history is some form of official documentation used for decision making - which is really scary (and lazy and full of potential errors and misinterpretations) - but that is a topic for another date.