Flums, your now a member of
http://sourceforge.net/projects/zimbra-xtras (We don't dump current there anymore - have to grab latest .properties files from perforce.)
Your welcome to svn commit or 'file release' a tar. Or still self host (though thread is obviously requesting a public archive.)
Some use it:
Finnish_fi/ 541 5 days ago meikka 5.0.16 version
Greek_el/ 540 13 days ago gmelis nomsg
While others like cvidal are members but don't use that route anymore - he just attaches files/links to forum threads for the French patch/dictionary/zimlet.
As far as shipping a language: We need it in the YALA translation system or someone has to manually compare/add lines each time.
Personally I think the 'stick a (beta) around it' and occasionally have you file a bug for us to upload into perforce sounds fine (just gotta convince the powers that be.) However, the issue with that is missing a new string can break features
[SOLVED] Share'ing of tasks, calandar and briefcase seems broken in 5.0.7
While I don't completely know how that software works, would be interested to know the effort required to add a new language to YALA, though not QA it, and just have any new strings pull from a dictionary till someone creates a bug and attaches edits.
For now, best to open an RFE to track interest in a language's official support (if made official the translation team can take a recent copy of it so were not going backwards in progress).