Internationalization, aka I18n for those l33t (elite) readers out there, is the process of removing any specific language references from your application. Typically this is accomplished in its simplest form with a simple map of key, value pairs for each target language and/or region.
Once this step is complete, the next phase is to localize (L10n) the application. While internationalizing an application removes all assumptions about a human language, localizing an application is ironically enough the opposite; namely, re-inserting human language and/or region specific requirements back into application albeit in a extensible fashion.
Why all this rather esoteric dribble about I18n and L10n? As of Rails 2.2.2, internationalization is a part of the base configuration. While you can still use such gems as gettext either directly or as the backend to Rails implementation, using Rails implementation is a great way to get started immediately. Which means it is possible to more easily add any number of languages to your Rails application.
Which is a lot of write up to say this: as of today I have included a first pass at internationalizing Kotoba. I still have work to do with messages, some less-used views, and emails; however, at present the application supports both English and 日本語. You can change your preferred language under Preferences. Give it a shot and tell me what you think.