The Times goes on to cite a figure of $650 Billion in productivity lost to multitasking. If the smart people at Microsoft can't get work done while checking email constantly, what makes us think we can? Seriously, although you can argue the magnitude of the number, it's clear that you can't just drop in and out of tasks without some startup time or switching costs. And if the magnitude is anything like 15 minutes, it's easy to see how you can spend a whole day getting nothing done if you check email every 15 minutes. There's even better discusison and analysis of this at Kathy and Dan's blog on Creating Passionate Users from which I'll pull two interesting and inspirational comments:

If you're a programmer, you know that context-switching in a multi-threaded system isn't 100% free. There's overhead with tiny bits of time lost on each switch, as a new thread takes control. Well, it's the same way with your brain. Only a lot slower.

do everything you can to resist the seemingly-intuitive notion that doing several things at once will save time. I know how hard it is to let that go, but study after study proves this wrong

So get out of the car, put down the phone, take off that stupid looking hat, and think hard about your consumption of microcontent in microtimeslices and see if that squares with the real goals of your life and your organization.