Translating Free Software?

InnerPeace Volunteers asks: "We'd like to translate our free software into other languages besides English. Our total budget for this is 0. Any suggestions on how to get this done?" The hardest part of getting people to translate anything, sometimes, is finding the talent to do it. Once done, it should be fairly easy to break things down into pieces and assign them to each person. Documentation is easy to translate, but how might code be best (re-)designed to make translating the programs internal dialog less of a bear for those working on the project? Is I18N still the best route for a multi-lingual program, or are there better options?