Yes, as you noted, you can get Spanish directions by simply append "tld=es" to the "Source URL" field. "tld" stands for "top-level domain" (like "com" or "es" or "jp" or "fr"). The default is "com", but you can replace "es" with just about any top-level domain as you like.

Obviously, it would be nice for me to better incorporate this into Maemo Mapper, and I've been meaning to do that for a while, but I've been busy. Internationalizing the web services is something I hadn't thought of, though.

Thanks for the feedback.