This is basically what I'm trying to do now. My entire career has been dominated by PHP thus far (though I've learned many other languages along the way). About a year and a half ago, I saw the writing on the wall and decided to learn something new. I chose Python as I'd heard many good things about the language, and it was more or less entirely new to me (unlike, say, Java or C which I had learned in college). It is so much more pleasant to code in than PHP. And I can't talk about it publicly quite yet, but good things are happening due to my Python abilities.