I don't see her being an enemy to the strawhat's. I could be and probably am completely wrong though. She doesn't seem to want to help them at all (the WG), and I think that she'll end up telling Luffy about Ace (probably not knowing that he's his brother) and then of course Luffy will flip and for whatever reason she'll assist him. It would give Luffy access to Ace since she would be granted access to the execuation. Like I said though, i'm probably wrong.

Also nice to see even more mention of this "Haki".