I've translated Plone in Greek for the needs of a website I had to make. The translation isn't tested by other users and perhaps it needs some improvements.
Anyway, it's not so bad and I don't think that there are huge mistakes in it. In fact I think that, if you need a Greek translation of Plone and you want it now, it's worth trying...
You can find the ".po file here":http://archangelos.objectis.net/plone-el.po/.
Please give feedback to "the author":http://archangelos.objectis.net.