Normally speaking I prefer to speak on the phone if I want a real heart-to-heart chat. Ignoring monetary concerns for calling between countries and so forth and the fact that I type a lot of words a minute, I will focus on what would concern Lois and Clark: work.
As someone who used to work in an office for 9+ hours a day, in and out of meetings, at my desk and so forth, IM is invaluable. When you're stuck in a conference representing your boss, you can IM discretely knowing full well that half the people are doing the same, tuning in only when the subject applies to their particular needs.
When you're at your desk and there are people waiting for a meeting right by it, you can IM and say things without having to be overheard. If you need a lapse to take a phone call, no problem having a message sit there for a minute or two.
There is also the always important "secret messaging" in order to rescue a colleague stuck in conference with someone who really is wasting their time. I can't tell you how many "important conference calls" I announced based on panicked IMs.
I assume the same would apply in a newsroom.
The ability to communicate without having to speak is becoming more and more important in some settings. Lois and Clark wouldn't be able to escape it because it is very much a fact of life now. I can't say it's all for the best, but that's reality.
