A new full installation, but can be copied over 3.x installations without deinstalling first. For pre-3.x versions, deinstalliung the old veriso9n first is strongly recommended.
http://www.esimgames.com/?page_id=1390
As far as I know this new build only includes some bug squashing since 3.024.
A new NavMesh builder is available, too (v12)