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: Quote, Profile, Research, Stock Buzz) 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: Quote, Profile, Research, Stock Buzz), Clearwire (CLWR.O: Quote, Profile, Research, Stock Buzz) and Google (GOOG.O: Quote, Profile, Research, Stock Buzz).

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."