"Unfriend" was declared to be the word of the year by the New Oxford American Dictionary. The word means to disconnect a link to someone within a social networking setting.
Most discussion on this matter has focused on the merit of the word - i.e. if it is valuable enough to be added to a serious dictionary and thus near-permanently inserted into the English language. But I take this debate to be moot. The word exists and it is widely used. It's hard to predict the future, but for now it is an important concept.
What intrigues me is the underlying reality that unfriend establishes. It depicts a world where friendship can seemingly be turned on and off with the click of a button. Although this might just be the digital method of a symbolic process which humans have utilized for decades, it connects a chillingly simple word to the deconstruction of a relationship.