1up reports that ATI has debunked a rumor that Xbox 360 could be upgraded to support DirectX 10 via a patch. "Xbox360 cannot run DX10," an ATI spokesperson told 1up. Currently, Microsoft's console runs an advanced version of DirectX 9, which, according to ATI, features "memory export that can enable DX10-class functionality such as stream-out."
It's difficult to say when and if studios that are developing cross-platform titles for Xbox 360 and Vista will hit a roadblock because of DirectX variances between the two platforms, but certainly a game like Crytek's Crysis, which does support DX9 with some DX10 features, could be optimized and ported to consoles.