I think canon is quite hard to pin down with something like Batman because there are so many different incarnations. No adaptation has truly followed the source material exactly. There's so much retconning in the comics, canon is hard to pin down. Each adaptation has followed its own course.
As for Catwoman, I would guess if Nolan uses the character he would use Selina Kyle who has always been white in the comics. That's not to say though she can't be played by a black actress.
Aside from cartoons, the only time the original Selina Kyle Catwoman has appeared on film was played by Michelle Pfeiffer in Batman Returns. Catwoman's true identity was never mentioned in the 1960s series, in fact she was three different women. Halle Berry's Catwoman was Patience Phillips. So I guess she's a character that is adaptable.
Even Selina's origins have been retconned over the years. I'd like to see Nolan use the prostitute version of Selina like in Frank Miller's Batman: Year One. I think that would fit very well with the escalating crime in his Gotham City.
