Here is a heads up for anyone using AutoCAD® MEP or anyone who works with those who do. While AutoCAD® Architecture 2008 uses the same file format as its predecessor, Autodesk® Architectural Desktop 2007, AutoCAD MEP 2008 does NOT use the same file format as Autodesk® Building Systems 2007. Apparently, AutoCAD MEP 2008 files will not be compatible with the 2007 releases.
While the Object Enabler site does not list anything for the 2008 products, an Object Enabler for AutoCAD MEP 2008 is available here. The site lists it being applicable only to the 2008 release of Autodesk products. The Readme does not indicate that installing the enabler would affect the format of any non-AutoCAD MEP files that were opened.