Some Xbox 360 owners won't be able to witness
James Cameron's Avatar (the game, that is) in its full 3D glory.
Luc Duchaine, the game's senior international brand manager, has confirmed that the game requires 1080p resolution for the 3D effect. Ignoring the fact that not everyone has their console hooked up to an HDTV, the only way you get that resolution from your 360 is using HDMI out. Earlier 360s did not have the appropriate port, meaning that early adopters are left in the technology ghetto.
The Wii version also won't have 3D. The only way it could have been done on the system is through those funky old red and blue glasses (anaglyph), but Duchaine said, "anaglyph doesn't offer a quality image, and quality is synonymous with the James Cameron name."
So... tough luck for some, basically.
Source: MTV Multiplayer