Speaking to Pro-G, Square Enix producer Hiromichi Tanaka confirmed that he was working on a new MMORPG bound for Xbox 360 and Windows Vista, adding "PS3 is a possibility." Ten months ago, Tanaka was saying just the opposite about the oft-hinted at MMO -- probably a sequel to Final Fantasy XI; possibly not. In April 2006, Tanaka confirmed the project for PlayStation 3, but made no mention of an Xbox 360 version. Now it would appear that development has shifted away from PS3 and onto Xbox 360.
Since Square Enix has already promised several versions of Final Fantasy XIII for PS3, it's in the company's interest, as a publisher concerned with multi-platform presence, to bring its next MMO to Xbox 360 first; a PS3 version could always come later. The project could also provide an opportunity to make use of Square Enix's recently acquired Unreal Engine 3 license.