Are the dynamic runtime libraries for Visual C++ (more specifically 2008) part of the Windows OS nowadays? I noticed that at least on Windows 8 you no longer need to ship these
In my opinion, the answer would be both: Yes and No.
Yes: More recent Windows OS are generally shipped with VC runtimes pre-installed (along with more recent versions of the .NET framework). It is because Microsoft uses the latest/newer Visual Studio before they release VS to the public (or even to MSDN subscribers). If not this way, whenever you install some application (legacy application or some downloaded application), the setup would anyway install the required VC++ runtime. Another way is through automatic updates.
No: In case where none of the above mentioned rules applies. Or, when the VC runtime shipped with a new service pack or a patch. You might have developed your application with newer patch/SP, and that must be installed (as Side-by-Side, of course).