The X.Org Foundation has finally announced the details concerning the 2013 X.Org Developers' Conference.
XDC2013 is happening from 23 to 25 September in Portland, Oregon. The brief conference announcement was sent out yesterday by Keith Packard to the mailing lists
There's also a Wiki page
for this development event that's not only about X.Org but also Mesa, Wayland, and surrounding projects.
Sadly though with the late announcement and the dates having changed from what was originally discussed, it's unlikely I will be at the event in person this year providing coverage on Phoronix, but videos are said to be made available this year via YouTube and there will be other remote coverage on Phoronix.