Not all social networks are about freedom of expression. Witness LinkedIn, a social network for business professionals that works very hard to keep things prim and proper. But now, LinkedIn will be going business casual, so to speak, by allowing its members to post photos of themselves.

While LinkedIn sees the photos as a necessary tool to remain relevant for its 14 million users, it won't let the pictures become a free-for-all.

[LinkedIn will] do everything we can to encourage it to remain professional," company spokeswoman Kay Luo told BusinessWeek.

According to officials at LinkedIn, the site may be planning more changes in the near future, including opening up the site to software developers who can build a range of applications for its users.

While LinkedIn may be looking to better serve its users, the changes come amid growing interest in the social networks. This week's news has been dominated by rumors that Microsoft is eager to purchase Facebook.