In the past the decision for site owners was always whether to build your own social network or find ways to include your site in other social networks. Traditional online thinking advocated building your own to maintain your metrics, but of course that meant you had to get everyone and their friends to adopt your social networking tools. Lately, the pendulum has swung the opposite way with sites including links to “share this” on facebook, digg, etc (see the link below every post on this site).
Facebook Connect takes this sharing a step further and allows users to their “real identity” from facebook into other sites. Facebook is pushing connect as a privacy tool where a users facebook privacy settings can follow them across the web to other sites. At the same time site developers are seeing facebook connect as a way to gain more information about their users and create a better profile to service more targeted (read higher CPM) advertising.