The biggest impediment to concentration is your computer’s ecosystem of interruption technologies: IM, email alerts, RSS alerts, Skype rings, etc. Anything that requires you to wait for a response, even subconsciously, occupies your attention. Anything that leaps up on your screen to announce something new, occupies your attention. … 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.
(thank you jon)