Semantic MediaWiki is supported for its localisation (L10n) and internationalizatiion (i18n) by the community of translatewiki.net. Translatewiki.net provides you with both a web interface for localisation as well as the possibility to export gettext (or .po files).
Every day, localisations are exported from translatewiki.net to the Wikimedia Foundation's Git repository. In this way the latest information is available for you for download.The message values of SMW have been translated, fully or in part, into over 80 languages. You can see the current translation statistics here on translatewiki.net. The current translations are available in this file
If you would like to help translate Semantic MediaWiki (and other MediaWiki code), there is a simple process for doing so: just register on translatewiki.net, then make a request on this page.
Translatewiki.net en 1.1.0