This is good news if you have need to use both Revit and AutoCAD Architecture.
Autodesk calls it Addressing Architectural Design Diversity.
AutoCAD Revit Architecture Suite 2009 now comprises AutoCAD, Revit Architecture and AutoCAD Architecture. The point release 2009.1 of Revit Architecture Suite 2009 will begin to ship 15th of September with no price change.
ACA 2009 as part of the suit will only be available to subscription customers.
If you are have network licenses of the AutoCAD Revit Architecture Suite you will need to request a new license file to be able to run also ACA as part of the suit offering.
AutoCAD Revit Architecture Suite FAQ with more details.