"If you think far enough into the future, and realize that the iPhone is essentially the Sputnik of next generation of computing and telephony, you’ll realize how important the development of presence technology will be in light of the 2.0 Address Book. Sure, the VoIP folks have known about this stuff forever, and CISCO even has a few decent products built on it, but I’m not talking about IP-routed phone calls. I’m talking about IP-routed people. Believe it or not, this is where things have to go in order for Google and Apple to continue their relentless drive towards ease-of-use and clarity of design.
In the future, you will buy a cellphone-like device. It will have a connection to the internet, no matter what. And it’ll probably be powered over the air. The device will be tradeable with your friends and will retain no solid-state memory. You literally could pick up a device on a park bench, login with your OpenID (IP-routed people, right?) from any number of service providers (though the best ones will be provided by the credit card companies). Your user data will live in the cloud and be delivered in bursts via myriad APIs strung together and then authorized with OAuth to accomplish specific tasks as they manifest. If you want to make a phone call, you call up the function on the touch screen and it’s all web-based, and looks and behaves natively. Your address book lives in Google-land on some server, and not in the phone. You start typing someone’s name and not only does it pull the latest photos of the first five to ten people it matches, but it does so in a distributed fashion, plucking the data from hcards across the web, grabbing both the most up-to-date contact information, the person’s hcalendar availability and their presence. It’s basically an IM-style buddy list for presence, and the data never grows old and never goes stale. Instead of just seeing someone’s inert photo when you bring up their record in your address book, you see all manner of social and presence data. Hell, you might even get a picture of their current location. This is the lowercase semantic web in action where the people who still hold on to figments of their privacy will become increasingly marginalized through obfuscation and increasingly invisible to the network. I don’t have an answer for this or a moral judgement on it; it’s going to happen one way or another."