It seems Egosoft are taking the same route opted for by Creative Assembly with Total War: Rome 2 and firing out the patches in public beta form before making them all official. Patch 1.18 beta is available on Steam right now.
via N4G: pc news feed http://n4g.com/news/1404226/x-rebirth-returns-to-beta-for-patch-1-18
via N4G: pc news feed http://n4g.com/news/1404226/x-rebirth-returns-to-beta-for-patch-1-18