According to this article IMing is toxic to Information workers. Here is a quote:
Our culture is hurting from information pollution everywhere we turn. The Internet is the most severely afflicted ecosystem, with countless content-free Web pages overflowing with either low-value stream-of-consciousness postings or bland “corporatese.” The physical world is not much better. In the United States, for example, you can’t buy a lawn mower without a label saying that you’re not supposed to mow your feet. Most instruction manuals are littered with “important” warnings that caution against obvious stupidities, burying actual dangers amid a mass of irrelevancy.