I think this is generally true, although I think there are a couple of languages that are exceptions just because they're so ridiculously complicated. C++, for example. A very practical language, but there are so many gotchas and traps in that language that most people learn the hard way, when they're debugging a corrupt virtual table jumping into god knows what. The thing is, there's probably like 5 people on the planet that actually completely understand all of C++.

Anyway I think most programming language knowledge transfers well, but for some languages years of expertise actually means a lot.