That's called a 'paceline', and is part of what makes cycling more interesting than something like running, IMO, because tactics matter a lot, and can vary a great deal with the terrain.

I agree. It was pretty awesome to be in a paceline for the first time. Something I forgot to put in the blog post was that one guy told me..."You're not responsible for the guy in front of you. You can't do anything about what he does. You're responsible for the guy behind you."