If a package creator wants to install different assemblies based on, say, the version of Razor used by a project, or of Entity Framework, she wouldn't have a good solution today, short of writing custom code to interrogate file versions is a powershell
script, to do so.
See the post at
for a concrete example of the problem.
We should provide a mechanism -- perhaps expanding our notion of a framework version in our folder structure -- to support this scenario.