I purchased my Xbox Premium in December 2007. According to wikipedia:
In July 2007, this version of the Xbox 360 began appearing with the Zephyr motherboard (the motherboard used in the Elite) which features HDMI 1.2 output and an improved GPU heatsink.
AFAIK, 3D requires HDMI 1.4, so can I get my Xbox to work with 3D? I currently only have component cables for it, and I don't find it worthwhile to purchase an HDMI adapter if it's not going to work anyway.