The whole Ketron crew is in Germany.
From Ketron site: We are sorry but we are unable to answer your e-mails from 22nd up to 30th March 2010.
Then they need some rest, then the Easter Holyday. Hope I'm wrong, but I think it will take sometime before we see OS4.
BTW OS4 should be done, in the UK they just got the Audya4 and 5, and I would think they have OS4. http://forums.ketronmusic.co.uk/viewtopic.php?f=3&t=715&sid=c85c4f04dc20f071e4696787f9e319af
Well, you never know if it's quite finished though.
[This message has been edited by skude (edited 03-26-2010).]