Learning a new language is a long-term process. In a couple of days you'll learn the basics, yes. But! As you probably know, the real practical applicability of any language is tied to the standard library and other available components. Learning how to use the efficiently requires a lot of hands-on experience.
Perhaps the only immediate short-term benefit is that developers learn to distinguish the nails that need a Python/Perl/Ruby -hammer. And, if they are any good, they can then study some more (online, perhaps!) and become real experts.
The long-term benefits are easier to imagine:
The employee becomes a better developer. Better developer => better quality. We are living in a knowledge economy these days. It's wiser to invest in those brains that already work for you.
It is easier to adapt when the next big language emerges. It is very likely that the NBL will have many of the features present in today's scripting languages: first-class functions, closures, streams/generators, etc.
New market possibilities and ability to respond more quickly. Even if you are not writing Python, other people are. Your clients? Another vendor in the project? Perhaps a critical component was written in some other language? It will cost money and time, if you do not have people who can understand the code and interface with it.
Recruitment. If your company has a reputation of teaching new and interesting stuff to people, it will be easier to recruit the top people. Everyone is doing Java/C#/C++. It is not a very effective way to differentiate yourself in the job market.
