Back in 1992, Focus on the Family translated the popular Christmas episode, The Visitors, into Spanish: Los Visitantes. That was the only Spanish version of an AIO episode at the time available at the time (not counting the Odyssey videos).
However, in 2010, the AIO team recorded in Florida with Spanish speaking actors to make Aventuras en Odisea, a Spanish adaptation of the radio series with a Hispanic town of Odyssey. The episodes starting airing last fall and the episodes are now available to download. So, if you're wanting to hear how AIO sounds in a Hispanic setting or want a fun way to learn Spanish, this is your chance. They have translated up to Album 4: The FUNdamentals. You can buy the downloads of all episodes released so far here.