Batman is officially cool in games again. The developer's impressive Metroid-esque Batman: Arkham Aslyum has resulted nearly two million copies being of the game sold already, according to a report in the LA Times. To keep the ball rolling, Rocksteady and Eidos are releasing downloadable packs for Batman: Arkam Asylum, based on a comment on the European PlayStation Blog.
The LA Times article does't specify whether Batman: Arkham Asylum sold or shipped more nearly two million, however. The difference is important. Shipped means the games are in the hands of or on their way to retailers with the potential to be sold, whereas sold means exactly what you'd think -- the games have been purchased. Based on today's NPD Group numbers, shipped sounds more likely.
As for the downloadable packs, little is known about them, but it's probably safe to assume they're in the same vein as the pre-order (Scarecrow) or PS3 exclusive (Joker) challenge rooms. The PlayStation Blog says two packs are on the way -- Insane Night on September 17 and Prey In The Darkness on September 24. Keep in mind, those are European dates. I should know more about the US soon