If you look around in the world of programming then most of the development work is being undertaken in Java, VB or C#. I agree with Martin when he says that most of the development work is centered around a particular language since learning more than one language turns out to be challenging but at the same time places a question mark on their efficiency as the field of IT witnesses changes at the drop of a hat. Programming is not just about languages but even frameworks which too at times can be difficult to handle.

It would be better if you try and learn new languages since it can change your viewpoint about programming and at the same time help in solving programming problems in several different ways. Try learning languages which one can differentiate since it can help in widening your scope of thought process.

Nowadays there seems to be a lot of attention being given for making environments which enable different languages to co-exist and we will see a trend where we will see programmers implementing more than one language in their projects and therefore one can safely conclude that we are not far away from the era of what Neal refers to as Polyglot Programming.