.Net 4.0 microsoft.vsa.dll

I have noticed that the Microsoft.Vsa.dll is installed with .Net framework 4.0 on machines that I use for development but on a regular machine it is not there.

The machine I noticed it missing on happens to be Server 2008 R2.

Is there a certain framework deployment I need to use to have that install with the framework?

I know the library is obsolete but it seems to be there sometimes but not others?

Thanks for any insight.

Sue