Comcast agrees to acquire Plaxo

Comcast Corp., the largest U.S. cable TV operator, agreed to buy online address book company Plaxo Inc. to expand into social networking and offer more services to its Internet-access and video customers.

Terms weren’t disclosed. The acquisition of closely held Plaxo will enable Comcast Internet customers to share online postings and information about viewing choices, said Sam Schwartz, a Comcast executive vice president.

Plaxo, which is based in Mountain View, Calif., has 50 employees and plays host to address books for more than 40 million people, according to its website. The company’s services enable Internet users to track other people’s online postings such as blog entries, photos and calendar entries.