Yes. It's official.See IMDb.
Personally, I think this is more imporant a piece of information than Ledger being Joker (which is also confirmed now).
But how cool (and somewhat risky, but who cares) that the films doesn't actually have "Batman" in the title.
I'm excited about this.
They actually announced the title at the same time they announced Heath Ledger was playing the Joker. But let's forget the fact that you're coming a little late to the party and embrace the fact that you showed up at all...
The title may be "The Dark Knight" now, but I'm betting somewhere between now and when we actually see the movie they're going to add a "Batman" in there somewhere. Because there's no way that Warner Brothers is going to let a franchise like Batman have a sequel where the franchise name isn't anywhere in the title.
If you're stupid, surround yourself with smart people. If you're smart, surround yourself with smart people who disagree with you.