...Well, we aren't sure yet.
There's certainly an implication that she said yes in today's Batman #25, simply because the issue ends with the two of them in bed together, but her left hand (where most people would wear an engagement ring) is obscured, and her right hand is naked.
Two weeks ago, Batman gave chase to Catwoman on the rooftops of Gotham once more, and upon catching up to her, he told her a story about the night they first met. Selina was attempting to steal a diamond that night, and though Batman caught her and took it back, he didn't just give it back to the owners.
Instead, he bought it, and in Batman #24 he takes it out and gets down on one knee to propose to the woman he's long loved, saying "I knew. Even at the beginning. I knew I'd need it. I needed it. Just like I need you."
Batman and Catwoman have circled each other for some time. From romantic flings to attempts at relationships and of course their ongoing adversarial relationship when she steals something. Still, this marks a new direction for Batman, if she says yes.
(You can see the proposal up close with spoiler images in the gallery.)
The story coming up -- "The War of Jokes and Riddles" -- is apparently taking place in flashback, and there are dark secrets in Batman's past that will come to light as he tells the story to Catwoman.
It's these admissions that will apparently test whether she can accept his darkest self, the way he apparently can, given that he knows seemingly everything about her.
But it may be a while before we find out for sure.