This module allows multilingual content to be imported using the migrate module. It (reasonably, I think) assumes that translations are identified in the source database with a language field and a common key that allows the language variants to be identified as a common translation.
To use this module, enable it as usual (its prerequisites, unsurprisingly, are migrate and i18n). Set up the site's i18n languages and create any migration content sets as desired. Then visit Administer > Content Management > Migrate > Internationalization to configure things. This requires two steps: first, identify the language field and the translation ID field for each content set; save these settings and then set up the language code mappings that correlate language codes in the source data with the enabled Drupal i18n languages. And then proceed to import your data as per usual.
So far this module supports migration of nodes and taxonomy terms only. And only fully multilingual taxonomy terms are handled properly. It is in very active development, as I am currently working on migrating a moderately complex trilingual (English / Hebrew / Arabic) site. As such, it is in a very idiosyncratic alpha state, but bug reports and feature requests are welcome.
Please contact us at http://openconcept.ca if you'd like to contract us to do specific work on this module.
[Marking as obsolete. Migrate has changed a lot since this module was created, and now provides native support for i18n fields.]