We've seen reports that Batman: Arkham Asylum has been released today in North America as expected, but have not seen an official announcement to that effect. What we have found is a new press release saying the Games for Windows edition of the superhero game is due worldwide Friday, but that is the game's PAL release date. Meanwhile it is available for online purchase through Direct2Drive and Steam as well as e-tailers such as Amazon. A playable demo was released early last month, here are some new screenshots, and here's that press release:

Tuesday 15th September/...Published by Eidos, Inc. under licence from DC Comics, the game features stunning NVIDIA® PhysX® technology that allows for the creation of incredibly realistic worlds full of interactive materials and objects. PC gamers can experience intense realism and fully immerse themselves in Batman’s journey into Gotham City’s asylum for the criminally insane.

Batman: Arkham Asylum exposes players to a unique, dark and atmospheric adventure that takes them to the depths of Arkham Asylum – Gotham City’s psychiatric hospital for the criminally insane. Gamers will move in the shadows, instigate fear amongst their enemies and confront The Joker and Gotham City’s most notorious villains who have taken over the asylum. Using a wide range of Batman’s gadgets and abilities, players will become the Invisible Predator and attempt to foil The Joker’s demented scheme.

Batman: Arkham Asylum for Games for Windows® LIVE will be available from Friday, September 18th, 2009. The game is also available for Xbox 360® video game and entertainment system from Microsoft® and PLAYSTATION®3 computer entertainment system.

For more information on Batman: Arkham Asylum, visit www.batmanarkhamasylum.com.