It should go without saying that you should be careful of what you "like" on Facebook. You should try not to "like" anything embarrassing or incriminating, lest it come back to bite you. A judge has ruled that "liking" something on Facebook doesn't protect you under the First Amendment, which is bad news for at least one man in Virginia.
Six people sued Sheriff B. J. Roberts in Hampton, Virginia after he fired them. They say they were fired for supporting his opponent in his bid to be reelected, which would be a violation of their First Amendment rights. One of the six fired, Daniel Ray Carter, "liked" the Facebook page of Roberts' opponent. Roberts claims they were either fired for poor performance, or because supporting his opponent "hindered the harmony and efficiency of the office."
Judge Raymond A. Jackson acknowledged that other cases involving written messages on Facebook protected the speaker with the First Amendment, clicking the "like" button is different and doesn't warrant protection.
A lawyer for the defense has already said they'll appeal the decision. This seems to be similar to the debate over whether or not Retweets are endorsements on Twitter, which leads to a lot of journalists including lines like "RTs do not equal endorsements" in their bio. Not everyone agrees the endorsement is necessary, and the debate can get a little ridiculous. The notion of a "like" implies an endorsement, but it's also the only way to subscribe to the updates from a particular page. Hopefully this won't lead to people writing that "Likes don't equal endorsements" in their profiles.