Knowing was released in Region A in the United States on the 7th of July, 2009. It contains the exact same extras as the Region All release for Australian consumers, released on the 29th of July. However, The Region A release has a higher video and audio bitrate than the Region All release. The video transfer is 30 gb for the Region A US release in comparison to the 21gb video transfer for the Australian Region All release. The Region A audio transfer has a DTS-HD MA track encoded at 3793 kbps whereas the DTS-HD MA soundtrack on the Region All Australian release is encode at 1934 kbps. (This may have been done to include the Dolby TrueHD 5.1 soundtrack also)
Knowing will be released in region B in the United Kingdom on the 3rd of August, 2009. I presume that this release will be identical to the Australian release.