According to Gamasutra, in October 2009, Microsoft removed support for third-party memory cards on Xbox 360 through a software update. As a result, it is reported that Datel, a memory card maker, filed an antitrust lawsuit against Microsoft alleging that said lock-out is deliberately harming competition. Microsoft is reportedly arguing that the lock-out was implemented to prevent cheating and to maintain tighter control over compatibility, safety and compliance and that it has a right to do so.
It has been reported that Microsoft recently filed a motion to dismiss the antitrust suit, using a precedent set by Apple to build its case. Apple sued Psystar last year for having manufactured devices that ran Mac OSX without Apple's authorization and was reportedly successful, despite Psystar's allegations of antitrust. It appears that Microsoft's argument is that, just as the Court ruled that only Apple machines can run Mac OSX, so should Xbox 360 consoles only use first-party accessories.
Microsoft has apparently also taken exception to Datel's definition of the field in which it claims anti-competition because it has only included Xbox 360 and PlayStation 3 and fails to include the Nintendo Wii, the Nintendo DS, the Sony PSP and Sony PlayStation 2 in its definition of "Multiplayer Online Dedicated Gaming Systems". Microsoft is allegedly arguing for the inclusion of the Wii, inter alia, in the category, because it has outsold both the Xbox 360 and the PlayStation 3, which may weaken the antitrust claims.
Coverage at: Gamasutra.com