Ray Ozzie's Has a Great Insight in Mobile technology

"Notification and awareness is one of the most interesting uses of wireless devices that has yet to emerge. We're moving into a world of pervasive awareness, where you can control the publishing of awareness of your location, "projecting" to others your interruptability and the modes of communications that you find the most useful at the moment. For example — when you're driving and have your hands on the wheel, you'd rather suggest to others that they call you rather than "texting" or emailing you. Or maybe they should just let you concentrate.

Projecting your interruptability to others might be really easy if we integrated our handheld wireless devices with our varied communication services. Take, for example, the phone. Why isn't it possible — without navigating a million menus — to slip a little button on the side to select one of four desired presence or interruptability states, customized to you: I'm in a meeting; I'm available to my "intimates"; I'm available for any interruptions; or "do not disturb". This state could be easily published by your wireless operator, through Web Services, to the on-line buddy list of your IM or email programs, or directly to other people's phones.
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http://www.gartner.com/research/fellows/asset_115813_1176.jsp