You may have seen this linked in several other places already: “The Autumn of the Multitaskers”:
This is the great irony of multitasking—that its overall goal, getting more done in less time, turns out to be chimerical. In reality, multitasking slows our thinking. It forces us to chop competing tasks into pieces, set them in different piles, then hunt for the pile we’re interested in, pick up its pieces, review the rules for putting the pieces back together, and then attempt to do so, often quite awkwardly. (Fact, and one more reason the bubble will pop: A brain attempting to perform two tasks simultaneously will, because of all the back-and-forth stress, exhibit a substantial lag in information processing.)
This idea isn’t new, but it’s always good to have incorrect conventional thinking challenged. Think of all the different ways software interrupts and asks you to multitask: IM conversations, Outlook & Gmail email notifications, not to mention temptations to interrupt yourself such as RSS readers or, uh… posting to the company blog.
37signals wrote a good post awhile back about the productivity benefits of disconnecting.