The August CACM contains an article "Understanding email interaction increase organizational productivity" (not online) which finds that it takes about a minute to resume work after being interrupted by an email notification. Which is kind of problematic if you set your email to check for new mail every five minutes! So I've set my email checking to once every 45 minutes and, even more importantly, I've slowed down my news aggregator to... once every six hours. I don't know if I can handle the information isolation, but I'm going to give it a shot.