The pinout has actually been posted on this forum (or AVS, I can't remember) and it's pretty clear there's no room.
Really? Got proof? Because that seems to contridict what MS reps have said several times now.
It’s a shame that it wasn’t connected via HDMI, but the Microsoft representative assured me that the 360 can output over HDMI, but that there isn’t a cable available at present.
http://www.trustedreviews.com/article.aspx?art=1803
Or.....
Microsoft just got back to us to clarify the Xbox 360's ability to transmit a digital signal. In short, it can, which means that Microsoft could conceivably release an HDMI cable for the Xbox 360.
http://gear.ign.com/articles/735/735860p1.html