This T-Nation article, The Third-World Squat, is the second time I've seen this particular stretch touted. First time was at the end of Mark Sisson's beach sprints video (more sensitively referred to as the Indigenous People Stretch). The Crossfit boards also picked up on these articles. Anyway, it's definitely one of the perfect stretches. Hits a lot of different muscle groups, proficiency will help with form/flexibility issues you might run into squatting or deadlifting, and you don't need a lot of room. I like to get out of my office chair every once in awhile, squat for a bit, then hit the camel pose (watch your back on this one, esp. doing it cold). To me this combination seems like the quickest and most efficient way to stretch out a lot of the stuff that shortens up when you spend too much time sitting.
Oh, one tip I don't think anybody has mentioned regarding the squat: if you can't get low while keeping your heels down you can roll up a towel and put it under your heels. That'll make it easier to get lower. After a few days, as you get comfortable, unroll the towel a bit. Repeat until you don't need the towel any more.
