There's a current scare going around FB that now that it wants to make some actual money, they'll start using profile pics and other things uploaded to facebook in advertisements.
Here is an example of the messages that get sent around:
On Friday, FACEBOOK will start using your photos in ads that will appear on the profile of your contacts. It is legal and was mentioned to you when you open an account. To prevent this do the following: Home -> Account Settings -> Facebook Adverts -> Adverts shown by third parties -> Edit third party advert settings, then choose "No one" in the list and save the changes. Copy this and paste in your profile.
I guess it won't hurt to have this confirmed or debunked here.