Frictional Games has released updated demos for both Penumbra: Overture and Penumbra: Black Plague which fixes some very important rendering issues with new ATI cards and drivers. The demos includes other fixes like crashes on certain configurations or even new solutions to some puzzles.

Penumbra: Overture v1.0.3 Demo (117.2MB)

Penumbra: Black Plague v1.0.1 Demo (133.41MB)