I had looked into WPML integration in the past, which is the only option for creating a multi-lingual site. While they were kind enough to provide a copy of WPML for me to use, integrating the WPML hooks was left up to me to code. I didn’t have weeks to spend reading their documentation and figuring out how and were to hook in their language engine. It is not as simple as “install plugin, add one line of code… done”.
Maybe it has improved since, however if someone does not sponsor WPML integration it won’t be put on the development schedule. There are many other projects that people are sponsoring that are getting priority these days.
I’d love to make Store Locator Plus integration with many different language products and make it a truly global product, but I need translators and code integrators to help make it happen.
All of the Store Locator Plus plugins do offer full internationalization/localization options provided by WordPress. Using Codestyling Localization (another plugin) makes it easy to translate the user and admin interface into any langauage, however I am only aware of being able to change from English to another language, not making it user-selectable for visitors to the site.