• Fortune, Tuesday, February 12, 2008 11 AM

There is a battle brewing for ownership of your address book. It all started when MySpace, Facebook and LinkedIn started asking users if they wanted to port their contact lists, giving them instant friends on their social networking profiles. The network effect [created by syncing contacts] is a prime driver of the Internet and is critical to the success of burgeoning social networks.

But who owns that data? It depends whom you ask. Google and Yahoo, which provide email and other contact-based services, let users control their contact lists, but Microsoft is less clear. The software giant has been sending cease-and-desist letters to companies that let users port their Hotmail contact. If they want access to Microsoft's users, they the have to make Windows Messenger available for 25 cents per user per year. The company says it would waive the fee if Windows Messenger becomes that site's exclusive IM client.

Still, the so-called DataPortability Workgroup is working on a set of standards that would enable data (photos, video, address books, etc) to move freely and securely from one Web site to another. This way, users would own the data, without security or proprietary interests becoming an issue.

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