I'm back in my home country, Turkey, for a few days now and I just heard about some discussions on singing star-spangled banner in Spanish.
Someone in an Orkut Community pointed out to this link where it is said that "U.S. Government Commissioned Spanish-Language ‘Star-Spangled Banner’ in 1919". What's more interesting is this link though:
In the early 1800's musical instruments and performances were not common in America. Music was generally imported from Europe, and popular tunes were frequently re-used as foundations for other lyrics. As an example, Maryland's state song, "Maryland, My Maryland" can be recognized as the German tune, "O Tannenbaum" (Oh Christmas Tree). Francis Scott Key used this English drinking song to set the meter of "The Star-Spangled Banner."