Well, most of the satellites will want to be in about the same orbit - the fairly common sun-synchronous orbit, that passes over the same spot on earth every day. They probably want to spread the satellites out over the orbit, though.

I'm not sure if randomness would be enough to do this, but if not, they could probably control things a little bit, at least for the Dove satellites (88 of them). Since the Dove satellites can point themselves to take pictures, my guess is that they can also choose to point themselves either perpendicular or parallel to the orbital direction. Since there's a little bit of atmosphere left up there, over time that should be enough to intentionally spread the satellites out.

This is just a guess, but I know similar techniques have been used in the past on satellites that were out of fuel - for example, Skylab.