The lights are on
Looks like players will indeed get dose of Harley Quinn in some new download content for Batman Arkham City.
Developer Rocksteady posted a teaser photo on its Twitter page this morning. Many commenters figured out the boots (and hammer) belong to Joker's notorious girlfriend.
Ten new purported trophies leaked earlier this month, suggesting the content will be based around single-player content. We'll hopefully get to know more about whatever this is sometime soon.