Hi Nick,
There have been several projects in Active Worlds for language learning. The public universe used to and still might have several worlds where visitors are supposed to speak (type) in a particular language. The software supports 7 language keyboards, I believe. Last year in AWEDU a graduate student was setting up a Spanish language learning world. I work with a teacher who plans to set one up for 8th grade Spanish. You might want to have a look at what they have done to help you plan?
Cheers,
Margaret