Linux' growing popularity outside the U.S. means its software experts should learn a lot of languages.
Take German, for instance, the native tongue of Stefan Esser from e-matters security. It was e-matters that recently revealed a critical buffer overrun error in Samba, a crucial Linux file and print server in many shops that maintain Windows desktops.>
But that's just the tip of the iceberg. Check out Linux lists you'll find a host of foreign languages written and spoken.
That's the way it works when anyone can be part of a solution. It's quite likely they won't speak your language, even if they're fluent in c.
If you're training an open source programmer at your home, make sure they study the languages of man, not just those of code.