Epic has confirmed that the Unreal Engine will receive an update later this month that will add support for Linux and SteamOS. That update will also see the free release of the Elemental tech demo used to show off the engine's various capabilities.
Epic have also released a huge list of alterations, tweaks and improvements that will be added to to the UE4 SDK for developers. Developers can sign up for UE4 for PC, Mac, iOS and Android for a monthly fee of $19, plus 5% of gross revenue from any products sold that use the engine.