There were some minor changes to the Revit Structure Suite package (specifically with AutoCAD Structural Detailing and AutoCAD) in 2010. I have had a couple of users ask questions about it and figured it was probably worth a post.
In 2009, the Revit Structure Suite shipped with Revit Structure, AutoCAD, and AutoCAD Structural Detailing (ASD). Users would need to install Revit and AutoCAD, and then ASD, as ASD ran off of AutoCAD.
This has changed slightly in 2010. Users are still shipped the same 3 discs, but ASD has its own version of AutoCAD for this release. So when you install ASD, you'll see that you get a shortcut to AutoCAD 2010 too.
The reason for shipping the separate AutoCAD 2010 disc was for users that didn't want to install ASD, or that were running on a 64 bit OS (as ASD won't install on that platform). So if you are running 32 bit machines and want to use ASD, you don't need to install the separate AutoCAD from the AutoCAD disc for ASD to run.