SAN FRANCISCO: Now Facebook has officially reached the milestone of 500 million users, the popular social network is preparing itself for future growth and the inevitable communications challenges ahead by befriending the PR industry.

Last week, the company invited a band of PR professionals to its Palo Alto headquarters where members of Facebook's in-house communications team gave an hour-long tutorial on how the site's tool can help PR pros. A few days later, Facebook launched a separate PR page as a discussion ...