Facebook will launch ads in your personal news feed next month, but you may not notice they are "sponsored stories" until you have already read them.
Basically if a friend of yours likes a page, let's say Dunkin Donuts, then you may see a sponsored story by Dunkin Donuts. There's no way to opt-out of seeing these ads except to remove it as it appears on your feed, according to CNET. Right now you only see these kinds of ads in the right-hand ticker.
U.S. & World
"You will only see Sponsored Stories in your news feed about your friends or people you are connected to," Annie Ta, Facebook spokesperson, told ClickZ News early this afternoon. "You will never a post from a page you are not a fan of, or from people who are not your friends. . . . We want to be really thoughtful about this, so we'll have a lot of rate limits in place. We hope to show people no more than one Sponsored Story in their News Feeds per day and we'll clearly label the story. They'll also be of the same size and treatment as other stories in News Feed."