Comcast acquires social network pioneer Plaxo

(Adds executives comments, details, background, bylines)

By Yinka Adegoke and Eric Auchard

NEW YORK/SAN FRANCISCO, May 14 (Reuters) - Comcast Corp (CMCSA.O) has agreed to acquire pioneering Web start-up Plaxo Inc, which was first to seek to turn address books into social networks and laid the foundation for Friendster and Facebook.

Terms were not disclosed. But a source close to the deal said Comcast, the top U.S. cable TV company and No. 2 broadband Internet supplier, is paying from $145 million to $175 million, based on meeting performance targets in the next few years.

Plaxo is famous in Silicon Valley for being early to see a business opportunity latent in users' e-mail address books, but only belatedly joining the social network craze that followed.

Comcast will use Plaxo to offer social network links across Comcast-connected devices from TVs to digital video recorders to, eventually, wireless devices, thanks to a new partnership with Sprint (S.N), Clearwire (CLWR.O) and Google (GOOG.O).

Plaxo joins the fast-growing Comcast unit that includes Comcast.net, video entertainment site Fancast, movie site Fandango and video publishing company thePlatform.

"Every social network is better the more end points you can connect with," said Sam Schwartz, executive vice president of Comcast Interactive Media. "Plaxo will offer users the ability to share with friends on all Comcast screens going forward."

Building on the idea that all people are connected by six degrees of social separation, while Plaxo has aimed to organize users' ties to address book friends, social networks link them to second- and third-level connections -- friends of friends.

To foster loyalty, Comcast is seeking ways to connect its 24 million users across its TV, phone and Internet platforms. It has worked with Plaxo for a year on integrating its e-mail and voicemail via a service called SmartZone for Comcast's 14 million-plus high-speed Internet subscribers and more than 4 million digital phone subscribers.

CALL IT A COMEBACK

Plaxo was founded in 2001 by two Stanford engineering students, Todd Masonis and Cameron Ring, and Napster co-founder Sean Parker, who was pushed out in 2004 by Plaxo's financial backers, only to become the founding president of Facebook.

Plaxo kept users in touch by automatically sharing data between their address books. But it irritated its fanatical early users with notifications whenever friends updated details

-- giving Plaxo a reputation as an accidental spammer. -- giving Plaxo a reputation as an accidental spammer.

In the last three years, Plaxo made a comeback by focusing on partnerships with big Internet companies to help synchronize address books and calendars with other Internet services.