Nvidia has released a small PhysX patch for Batman: Arkham Asylum title.

Update [30.01.2012]: Newer version of RRB library is available, to ensure compatibility with 4xx/5xx series GPUs.

Patch for owners with GeForce 400 Series cards and up and Batman: Arkham Asylum game.

Requires: R290 Graphics driver or greater.

In order to experience Batman: Arkham Asylum to its fullest extent when running PhysX on
Geforce 400 Series cards and up, users will need to replace the existing RRB.DLL file with
a new one. By default, the RRB.DLL can be found in one of the following directoires
depending on the version of Batman Arkham Asylum:
“…\Square Enix\Batman Arkham Asylum\Binaries”
“…\Square Enix\Batman Arkham Asylum GOTY\Binaries”
“…\Steam\Steamapps\common\batman arkham asylum\Binaries“

Where the … is replaced by one of the following depending on the OS version and if it
is a Steam version of the game:
C:\Program Files\
C:\Program Files (x86)\

If it is not located in this directory, please do a search for the filename
on your system.

The CUDA DLL cudart32_41_0.dll must also be copied to the same Binaries directory where
the RRB.dll file is located.

RRB.DLL is responsible for GPU accelerated Rigid Bodies calculations – large-scale physics effect, mostly memorable from Scarecrow nightmares.

You can download PhysX Rigid Bodies patch from here (3 mb).

Thanks to Stefan for update.