I agree with Sam Ruby: a successful tech is a diversified one. You can’t always depend on a new millennium to justify sticking with one and only one programming language.
This last week I worked with Java, JavaScript, PHP, Python, and Ruby. I had been on a long hiatus from Java after the end of the dot-com era, but now I’m back and plan on sticking it out with the language. Yes, even unto J2EE.
I also agree with Michal Wallace: you are more likely to have an easier time getting work if you focus on .NET than Python. In some ways, I think that the interest in Ruby has slowed the interest in Python. Sure you can work with both languages: but why would you want to?
In St. Louis, the demand is for .NET (VB or C#) or Java. That’s it. I mean, that’s really it. Most of the other work in PHP or Python or Perl is off-shored.
When I move to the northwest, I imagine I’ll either need to get back into .NET or brush up my C++ skills, in addition to the Java. If one has up to date C++ skills, one can usually find work.
As for JavaScript — every web developer should be proficient in JS. Eventually you’re going to want to validate a field before sending it to the server, or have to muck with cookies. There will always be someone somewhere who will say, with breathless excitement, “What about AJAX?” JS is ubiquitous.
PHP is also ubiquitous, but there just isn’t the work for it. Nor Python. Perl’s fading. I have my eye on Ruby, though.