I've spent several hours today fighting with Enterprise Library (EL) trying to strong name the assemblies for deployment to the GAC on my test server. The January 2005 release of EL was relatively easy to build: open solution, add keyfile attribute to global assemblyinfo.vb, and build. You do have to fix any broken references before building, like references to the nunit framework if you don't have it installed.
The June 2005 release was a bit more difficult. When building, the IDE always errored with the message “Referenced assembly 'Interop.MSDASC' does not have a strong name”. Fortunately, after much frustration I came across this post by Erwyn van der Meer, which outlines the steps for solving this little problem and gives a good explanation as to what actually causes the problem.
After following his steps (actually the steps he got from this Microsoft KB article), I was able to strong name the EL assemblies and build the solution without any problems.