Consider this another rumor squashed as Bungie has confirmed that Halo: Reach will definitely not feature 3D of any kind after reports from earlier today suggested it might. Instead, it is the result of a marketing gimmick from a TV manufacturer.
Earlier today we reported on a story about Halo: Reach being shown in 3D at GamesCom. Was Bungie sneaking in an unannounced 3D update or was this a clever marketing ploy? The latter appears to be the case according to Bungie.