Tag keys and values (values other than names) are all in English within the database, and likely to remain that way. Tag data given back by the APIs, and ultimately shown/entered within the editing interfaces are also all in english at the moment. It would be possible to define mappings to mask this, but those technical challenges have not been tackled seriously by anyone as yet. Translation efforts around tagging interpretation have so far focussed on descriptions of what the tags mean within the wiki (see below) - Chris Blow