The mysterious "fourth console" that was on stage at the Microsoft press event and then surreptituously removed before it began was the rumored additional Xbox 360 SKU-- it's a special edition of the 360 for Halo 3, with a green and orange color scheme. No word yet on specifications.

UPDATE: Bungie.net's post says the console has HDMI, so possibly the other specs are also the same as the 360 Elite.