The December Cumulative Update was released on December 16th. The next Cumulative Update (CU) is scheduled for the end of February, then Service Pack 2 will be available between February and April and it will include the February CU.
From this point forward each Cumulative Update will consist of a package that contains the latest of every hotfix patch that we have shipped. What this means is that if you build a new Project Server 2007 farm, you can apply the latest service pack (Service Pack 1), the latest WSS CU package and the latest SharePoint CU package and be completely up-to-date. The package includes the Infrastructure Update, there is no reason to install it separately (but you still need to install SP1).
Please refer to this TechNet article for deployment guidance: Deploy cumulative updates (Project Server 2007)
After applying the December CU, the file version should be: 12.0.6334.5000
Knowledge Base Articles and Downloads
· Announcing the release of the October Cumulative Update for Project and Project Server 2007
· Announcing the release of the August Cumulative Update for Project and Project Server 2007
· Upcoming Microsoft Project 2007 and Project Server 2007 Service Pack 2
· Cumulative updates are available from the Microsoft Office team to deliver hotfixes for reported problems
· Project Server TechCenter (TechNet)