I have been running the CS6 beta for a while now. I believe it may be causing and issue on the Mac when installed along side CS5. There are updates available based on my search for ACR6 as compared to my current version but Appliation manager indicates that CS5/ACR6 has no updates available. I noticed this when I received my D800 a few days ago. So...
1) There is a version of ACR 6 that supports the D800
2) Application Manager thinks that everthing is up to date.
3) ACR 7 does not seem to support the D800
Here is an explanation of the camera support in each version: