Adobe has been flooded with similar questions on the Adobe Photoshop forums.  The answers from Thomas Knoll and the other Photoshop gurus are that ACR is updated 3 or 4 times per year to add new cameras, so people should just be patient.  The process of adding support for the D2X is complicated by the need to reverse engineer the structure of the NEF file, which Nikon treats as proprietary.  I expect an update will be available for download in due course.

Does anyone have any idea what to expect from Adobe for D2X support for ARC?  Will this be available as a download?  How long does it generally take for Adobe raw converter support for new camera models?  How long did it take for 1ds?  Is there ARC support for 1dsMKII yet?