In what will most likely turn out to be a trio of class profile pieces, IGN brings us some hands-on details about how the rogue is being implemented in BioWare's forthcoming Dragon Age sequel. It sounds like the specializations aren't getting a whole lot of tweaking:
The rogue, like other classes, can be built out to enhance certain traits. Assassin, Shadow and Duelist are all specializations available to the rogue, and each offers a unique way to slay enemies.
Assassins are trained in the Antivan traditions, so they are able to mark their foes and call out a target's weaknesses to their allies, which helps increase the party's damage against enemies.
The stealthiest of all the rogues, Shadows are able to slip away at any moment in battle, lay low in the dark and then wait for the perfect time to strike.
The Duelist, though not as stealthy as the Shadow or as accurate as the Assassin, is extremely difficult to hit, so you can feel free to taunt your enemies while you hack away at them.