http://www.macnn.com/articles/11/09/20/support.for.mac.lagging.behind.pc.consoles.ios/
Unreal Engine 3-ready UDK reaches Macs
updated 02:55 pm EDT, Tue September 20, 2011
Support for Mac lagging behind PC, consoles, iOS
Epic Games has released a new beta of the Unreal Development Kit, at last bringing Unreal Engine 3 game creation to the Mac. The current iteration of the Unreal engine is a gaming industry standard, used by many major titles like Batman: Arkham Asylum and Epic's own Gears of War series. Until now, though, the UDK has been Windows-centric, regardless of the target platform.
The new UDK also incorporates multi-display support for iOS, whether through AirPlay or HDMI. The Unreal engine currently has a limited footprint in the iOS world, the main example being Epic's Infinity Blade. LucasArts and Gameloft have promised to join the field in the near future, however.
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Joined: Sep 2011
This article is misleading
Epic have only announced that the latest UDK allows the creation of games that run on the Mac. The UDK itself is still Windows only.