Reed Albergotti:

Facebook Inc.’s move Wednesday to let teenagers share items more widely reflects growing competition among social networks for the attention of teens–and the advertisers that want to reach them.
Facebook said it would let users between the ages of 13 and 17 make posts “public” so that they can be seen by anyone on the network. Previously, teenagers’ posts could be seen only by their friends and “friends of friends.”
With the shift, Facebook will operate more like such rivals as Twitter Inc. that let teens share publicly. Twitter, unlike Facebook, also lets users post anonymously or with pseudonyms.
Analysts said Facebook risks losing the next generation of young users if it doesn’t keep pace with competitors. But some privacy advocates are more concerned about public posts on Facebook than on other sites because of its vast reach. It has 1.2 billion users world-wide, roughly five times as many as Twitter. Facebook also allows users to post a wider range of media and to comment more broadly than Twitter does.
“This is about monetizing kids and teens,” said James Steyer, founder and chief executive of Common Sense Media, a nonprofit devoted to online privacy.
Aaron Everson, president of Shoutlet, a Madison, Wis., company that helps brands manage social-media campaigns, said Facebook wants to “compete against other networks that might have a younger demographic, and potentially help them reel in more advertisers.” Marketers will have to be creative in grabbing the Web-savvy teen’s attention without alienating parents, he added.