• Added a new ambient occlusion method: multi-scale volumetric obscurance.
• Added support for custom AO color.
• Added a NaN killer (enabled by default).
• Added an "anamorphic" setting to bloom.
• Added alpha-propagation to most effects to allow post-processing to render against a transparent background.
• Lens Dirt now keeps its aspect ratio.
• The package now automatically sets a global define (UNITY_POST_PROCESSING_STACK_V2) when it's imported (can be used to check if v2 is currently available in the project).
• Fixed various bugs and platform compatibility issues.

Full changelog.