A worm is spreading through Facebook that forces users to "like" a post. The worm began as an a javascript exploit that automatically activates the "like" functionality from a link. The attack was distributed through an article titled "Shocking! This girl killed herself after her dad posted this photo."
Note: This was reported first from Mashable and Jesse Stay of SocialToo. The worm does not seem to steal information from users' Facebook accounts, according to Mashable.