Cory Doctorow tells us how he manages to write a book a year, half-a-dozen columns a month, plus plus plus, in a world of ever-present Internet distractions.
By all means, schedule a chat — voice, text, or video — when it's needed, but leaving your IM running is like sitting down to work after hanging a giant "DISTRACT ME" sign over your desk, one that shines brightly enough to be seen by the entire world.
I have the same opinion of coding. When I really need to concentrate on getting some code written, I need to kill Skype, iChat, and facebook, even if for 30 minutes.