+1  A: 

You can get the source here: http://www.codeplex.com/unity

Brian
A: 

Have you tried on this site? http://unity.codeplex.com/

Andy White
yes, but it's not the same. I have Microsoft.Practices.Unity and ObjectBuilder2 that came with PRISM. I tried replacing the references to this project instead, but it doesn't work.
Teodor
A: 

I got it as part of the Enterprise Library

http://www.microsoft.com/downloads/details.aspx?FamilyId=1643758B-2986-47F7-B529-3E41584B6CE5&displaylang=en

Here's the source control checkin list. You can download whichever version matches the one you have.

http://unity.codeplex.com/SourceControl/

looking....

Will