For instance, Facebook writes of its chat heads feature:
With chat heads you can keep chatting with friends even when you’re using other apps. When friends send you messages, a chat head appears with your friend’s face, so you see exactly who you’re chatting with. Messages reach you no matter what you’re doing – whether you’re checking email, browsing the web, or listening to music.
Is that a feature or a threat?
Here’s the thing about apps, and on a larger scale, technology that people love – no matter how much someone is into something, they don’t want it thrust in their face 24/7.
As someone who owns a cellphone with text message capabilities, and a frequent user of an IM application, I can categorically state that this sounds horrible. I like chatting with friends — who doesn’t? — but the constant bounce of the dock icon or the vibration of my phone can be so distracting that an otherwise enjoyable activity can feel like a chore.