So at work we use Windows Messenger, the idea being that we can communicate quicker.  This should be the case, but I’ve found that the vast majority of people here (mostly those older than myself) use it for:

Got a minute?  Stop in my office.

or

 Got a minute to discuss X?  I’ll call.

or

Are you there?  I’ll be over in a second.

Sigh.  Come On people!  Don’t be afraid to use IM.