I ran across a similar rumor about Jolie on latinoreview.com
but this is the first I've heard of the Riddler. As for the Penguin, I read an article stating that this character wouldn't fit in with Nolan's concept of Batman's universe. I agree--this would be a bad decision (and he hasn't made any bad decisions so far, so I'm hopeful that I'm right).
As for Depp, he's a decent actor but he wouldn't be a good Riddler. He's too closely associated with Tim Burton and I suspect that he'd bring some of that to the role, which is precisely what these movies don't
need (and haven't had).\