DIY Laser Microphone

At times (can't think of specific examples) I've seen movies (or watched TV shows, or read novels or comic books) in which someone eavesdrops on somebody else by pointing a laser at a glass window separating the speaker and the eavesdropper: the idea is that the speaker's voice vibrates the glass in a way that the laser can detect. I figured that was science fiction, but a recent LifeHacker post suggests that it's possible, easy, and inexpensive. Pretty cool.