[halostatue]

In human languages, I'm strictly monolingual, but I have retained enough French that I can read (easy) French articles, some Spanish writing, and some Italian writing. I recently went to the Dominican Republic and did OK with the Spanish that I had to use there (which, granted, was minimal); a longer trip to Italy required more knowledge of Italian, but I picked up enough to be able to order dinner and ask directions while there.

On the programming language side, however, I've learned ~25 programming languages and dialects (ksh, bash, and zsh are IMO dialects of sh) and probably use ~6 of them regularly. I suspect that your intuition about how programming languages can affect people this way is correct, but because (as radicalbyte said http://news.ycombinator.com/item?id=3720212) programming languages have simpler grammars, one need be fluent in more than one programming language to get the benefit of being human-language multilingual.

I do know that knowing more programming languages has made me a better programmer—I can think about the problems that I solve differently, and can adapt the idioms from one language (such as an Enumerable#any? from Ruby) to another language (implementing something similar for anonymous delegates in C#). I've also found that, by and large, I learn new programming languages and idioms faster now than when I first started and only knew a couple of languages.