I wonder why would a C++, C#, Java developer want to learn a dynamic language?
Assuming the company won't switch its main development language from C++/C#/Java to a dynamic one what use is there for a dynamic language?
What helper tasks can be done by the dynamic languages faster or better after only a few days of learning than with the static language that you have been using for several years?
Update
After seeing the first few responses it is clear that there are two issues.
My main interest would be something that is justifiable to the employer as an expense.
That is, I am looking for justifications for the employer to finance the learning of a dynamic language. Aside from the obvious that the employee will have broader view, the
employers are usually looking for some "real" benefit.
Dynamic languages are fantastic for prototyping ideas. Often for performance reasons they won't work for permanent solutions or products. But, with languages like Python, which allow you to embed standard C/C++/Java inside them or visa versa, you can speed up the really critical bits but leave it glued together with the flexibility of a dynamic language.
...and so you get the best of both worlds. If you need to justify this in terms of why more people should learn these languages, just point out much faster you can develop the same software and how much more robust the solution is (because debugging/fixing problems in dynamic languages is in my experience, considerably easier!).
Why learn Perl, Python, Ruby if the company is using C++, C# or Java as the application language?