it all depends on the architecture (Score 1)

it really all depends on the architecture. the idea of just writing parts of an application in different languages is nothing new, and certainly is not a bad idea since different languages might have different strengths. but the idea of just hooking up code developed using different languages, doesn't make much sense. instead, if the given application has the necessary architecture support this is another story. for example, you make your application modular, and allow then for on the fly addition of modules written in different languages. still, regardless of how it is actually implemented, one of the strengths of mixing languages in a development could be the ability of allowing, lets say, users to modify the behavior of your program in a controlled manner.