Click the tiny little running man icon under your character portraits - changes to a hand stopping symbol. Or press H on the keyboard - same effect. You can then move then individually and this is essential in some fights where you don't want fighters dashing off into an inferno spell you've just cast
Rogues have several uses - disabling traps, picking locks and fading. I still reckon they'll patch in a knock spell or something though it just feels wrong the way it's done atm.
Also: http://www.theregister.co.uk/2009/11...ou_dragon_age/