Microsoft appear to have accidentally announced the existance of an upcoming HDMI-enabled Xbox 360 edition via the XNA Game Studio Express forums they run. XNA is the application that allows you to "create your own games" and one developer asked whether the new HDMI-enabled edition of the Xbox 360 will require coding changes - "Will the HDMI output on the revised 360 require any code changes?"
A Microsoft employee then simply replied "no changes required."
And there you have it, no rebuttal or denial, instead the best form of confirmation that we have thus far that the "Xbox 360 Elite" is indeed on its way. As the XNA forums ask of dicussion topics there - "what this post helpful?" Very.