I am just returning from an event where someone approached me well after to ask a question. This person had heard that Service Pack 1 was available for Vault 5. The question was "Should I install this service pack because the Readme file does not mention Civil 3D at all?"
My answer was based on the following comment by Anthony Governanti, Autodesk Technical Marketing Manager, in the discussion groups on September 5th, 2006.
"Just a quick update on this; we are still working through the testing on the Vault sp on Civil 3D. For now, please do not install the patch until we make an announcement and give the go ahead."
At the moment, this is the last information that I have heard or read about this matter, and until told otherwise I suggest that it be the current coarse of action.
If anyone else has any sort of update many would benefit from this sharing.