The beta 4 series will be the last set of betas prior to release. Users who want to pre-order and beta test the stand-alone game (as opposed to Drengin.net) will only be able to do so for a short amount of time. After we go into release candidates you will have to wait until the game ships to get it.
Stardock is about to sign a publishing deal with a major retail publisher which will affect the release date. We expect to go gold near the end of this month but general availability will likely be mid July or early August due to retail manufacturing/marketing/distribution set up.