Facebook isn't just eager to overtake MySpace as the premier social network; the site also is interested in lucrative niches. A small change at Facebook that allows users to segregate work friends from social friends could mean increased competition for the business networking site.

"They've got to see this as a major threat," Jupiter media analyst Barry Parr told CNN/Fortune. "At some point people are going to want to simplify their networking activities. The open question that no one is really prepared to answer yet is how many networks do you really want to belong to?"

While Facebook is looking to become a focal point for business and play, LinkedIn is standing still. Last week, the site made headlines when it reversed its policy against headshots, encouraging users to submit tasteful pictures.

LinkedIn also said Facebook isn't well-positioned as a business tool.

"We consider ourselves a professional network," said LinkedIn communications director Kay Luo. "The thing about Facebook that prevents it from being useful the way that LinkedIn is useful is the search capabilities."