I attended the OC Flex User Group tonight  where Iman Khabazian gave a presentation on  SCUGE.  SCUGE is an open source framework used to develop Flash/Flex games that will eventually become a game engine. It incorporates MVC and looks like a great framework for game development. I noticed that the presentation was being video taped so maybe it will be posted online in the future. Until then you can read more at www.scuge.com.