In August 2007, Plaxo, a Silicon Valley company that made its name with an online address book technology, decided to add some features to its service and launch a full-blown social network. At the time, even Peter Curley, a Plaxo product manager, approached the move sardonically. He titled his blog post introducing the service (known as Plaxo Pulse) with, "Oh geez, not ANOTHER social network."

Now, more than a year later, has Plaxo made a spot for itself in the crowded and competitive social networking field? Plaxo users still admire the service's address book technology and its ability to thoroughly manage their contacts across different e-mail systems. But on the whole, users interviewed for this article say they're lukewarm or cold to the addition of Pulse, the social networking tool.

Still, because of Plaxo's addition of Pulse and their garnering of a largely professional user base, it is viewed as a modest competitor to other social networks in the valley, particularly LinkedIn, the most well-known business-minded social network that recently took a round of $53 million in funding, valuing that company at $1 billion.

Plaxo, for its part, was acquired by Comcast in May for a rumored $175 million (the actual price went undisclosed), signaling that a major media player sees a bright future for the service.

Even given this injection of capital, however, analysts say it remains unclear if Plaxo can lure users away from LinkedIn's massive user base of 29 million members.

"LinkedIn blew Plaxo away in terms of the number of business users," says Aaron Mentzer, a public relations manager at AtTask (a software company) and who uses both Plaxo and LinkedIn. "Most services go through your e-mail contacts and let you know which of your e-mail contacts already use the service. [For me] LinkedIn generated probably 40 to50 matches; Plaxo probably generated 4 to 5, all within my company."

Analysts and users also say Plaxo may have gotten in over its head with Pulse. The service allows users to share pictures, status messages or bookmarks with one another, dipping Plaxo's toes in an even more dauntingly broad part of the social networking market dominated by Facebook and MySpace — taking on a challenge that some analysts say is all but insurmountable.

"They can't compete with Facebook on the consumer side, and they're a distant second to LinkedIn on the professional," says analyst Jonathan Yarmis, a VP with AMR Research.