On heise Developer there is a nice article about the role of the programming languages for developing software today (in german): Polyglot Programming, oder: Wie Open Source das Programmieren veränderte.
In the conclusion the author Dj Walker-Morgan says (my translation):
"What you can learn is programming – not only a language, but as many idioms as reasonable in your time. You should learn the ideas and stylistic elements, not the specific capabilities until you know the language fluently."
This nicely points out something I consider important in software development today.