Definitely not a direct correlation to intelligence. Unless someone is truly mentally retarded (using "retarded" in its actual sense, not in a derogatory way), anyone can learn a language other than their native one if they put enough work and discipline into it.
I do agree, though. Someone from another country could not speak English very well, and that's considered normal, but if an American doesn't speak a foreign language perfectly, they're considered dumb or stupid.
