I was trying to explain the concept of Ployglot programming to someone but couldn't find a clear definition. I stumble on this link recently: Polyglot programming.
...writing good multi-threading code is hard. Very hard. So why bother? Why not use a language that handles multiple threads more gracefully?
Need a nice web-based user interface? Why not use Ruby on Rails via JRuby
It's all about choosing the right tool for the job and leveraging it correctly.