
Hang on though, this is a Christopher Nolan movie, so don't expect everything to be clarified.
In the release Cotillard is said to play Miranda Tate, a board member at Wayne Enterprises, with JGL playing a cop. Not exactly instantly recognisable characters but certainly ones which could fit into the Nolanverse Batman lives in. However, as has been pointed out by some already (including Variety, after the release), neither are established characters and also, Nolan hardly picked these two to fill small background roles. If you'll cast your mind back to Batman Begins, Ras Ahl Gul (Liam Neeson) was, at first, known as Henri Ducard - and for a long time Cotillard was rumoured to be his daughter...
Gordon-Levitt was rumoured to play the Holiday Killer, a serial killer son of Carmine Falcone, the mob boss seen in Batman Begins also. Of course, there could be some twist in this in the film but it's not a far shot to imagine both characters are being used to tie up some loose ends perhaps.
Whatever Nolan has planned for them, it's great that they're officially signed on. The Dark Knight Rises opens next summer, and you can expect plenty more slivers of information to seep out slowly before then, culminating in a trailer that makes people rightly go absolutely insane with excitement.