Well written and witty article in the Atlantic about fMRI imaging studies of people performing multitasking activities. Technology has been the driving force behind the current enthusiasm for multitasking but these studies show that multitasking actually makes people less efficient.
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.)
I think that technology can be a significant productivity enhancer in the interstitial spaces, those places and times between others. Waiting for the bus, in the airport lounge and other low cognitive intensity situations. If you are going to have technology that has access to you at any moment, instant messaging, blackberry etc they need a contextual awareness as to what you are doing what the message is and whether it is appropriate to interrupt you in order to deliver that message. As we become more connected we have to become more discriminating. Not all information has the same value, but at the moment we are forced to absorb the information before we can make a judgement to it's value, distracting us from our intended goals. I see this contextual/semantic understanding as the next major evolution of mobile devices.