I'm using MEF to get a modular application and compose it at runtime.
I have a Library that is referencing the IronRuby DLLs and that initializes the IronRuby context.
I put all my module DLLs (and its depending DLLs, like IronRuby*.dlls) into a separate "Modules" folder. The executing Assembly is at the same directory level as the Modules folder (but not "knowing" from the module DLLs until compisition).
 
When the Ruby engine gets created it doesn't find the IronRuby.dll and I get a FileNotFoundException. It has something to do with the location of my DLL in the subdirectory, because when I copy the IronRuby*.dlls to the directory where the exe is located everything works, but I want the (for the Application not relevant) DLLs reside in the Modules directory.
(The IronPython code works btw.)
 
My code is on github so feel free to test it out: https://github.com/toburger/RulesEngine