When you install Revit, you notice that the Vault Addin does not appear like it should do.
The Vault Addin wont appear until you enable it within the Vault client installer first. So go>Control Panel>Programs and Features and Select the Vault Client you have installed.
Until the Autodesk Revit 2012 Add-In is ticked the it wont appear.
Once you enabled, you would need to restart Revit for the toolbar to appear