Plaxo turns address books into Web social networks

By Eric Auchard

SAN FRANCISCO (Reuters) - Plaxo, which makes software for PC users to keep address books up-to-date, said on Sunday it is helping millions of members open up their online datebooks to build social networks like MySpace or Facebook.

In a major comeback push by the 6-year-old company, which Silicon Valley insiders see as a forerunner of the social-network craze, Plaxo has created the first Web service to share data between major address and calendar programs.

With Plaxo 3.0, as the new service is known, consumers can synchronize address books and calendar data locked up inside Microsoft Outlook, Googleand Yahoo services, Apple Macintosh computers, Mozilla Thunderbird e-mail and many mobile phones.

Now Plaxo is going head to head with social networks, which rather than forming links between computer address books link people online through their shared media interests -- based on what they write or the photos and video they choose to share.

Plaxo plans to let friends keep track of their contacts' Web surfing habits, paralleling a feature fuelling the rapid rise of Facebook, which allows users of all ages to create private networks to connect to their immediate friends. Watching and learning what your friends are doing on the Web -- and being watched yourself -- is today's hottest online trend.

"The most important things happening right now on the Web are about people's relationships with other people," Chief Executive Ben Golub said in an interview. "There is no reason to segment your relationships with others based on which applications you use."

Plaxo previously enabled individual users to stay in touch by automatically sharing data between contacts' address books. It has signed up more than 15 million registered users to date, although the number of active users is unknown.

Plaxo functions like a network of address books. When a phone number of someone's contact changes it automatically updates in contact address books, assuming the contact gives permission via e-mail.