We haven’t the slightest idea what the free Batman: Arkham Asylum DLC is -- other than it’s downloadable and it’s content -- but here’s one confirmation: it’s hitting all the platforms the game graces simultaneously. See, PC people? Eidos is demonstrating that the world is not such a cold and shallow place for your kind.
The multi-platform release confirmation comes from the official Batman: AA message board, in a topic devoted to the DLC’s release. An Eidos representative (and moderator) swooped into the conversation and wrote, “I'm happy to inform you, it will arrive at the same time.”