Details about this year's event can be found on the X.Org Wiki. If you are an X.Org developer or otherwise involved with and/or interested in X, the sign-up sheet is here.
So far there's a collection of the usual names that Phoronix readers are used to seeing mentioned in regards to Mesa or X.Org: Daniel Stone, Alex Deucher, Peter Hutterer, Jerome Glisse, Martin Peres, Ian Romanick, Jesse Barnes, Keith Packard, etc. I think David Airlie as well (at least a second Red Hat employee from Australia, besides Peter Hutterer), but no word if John Bridgman will be attending to further represent AMD's open-source team. The overall attendance level is expected to be around 60.
If you're not able to attend in person, I'm hoping to offer a Ustream live video stream of the event. However, it might turn into just uploading the recorded audio/videos later on. Regardless, it should be good though as my home/office is only 20 kilometers away from the Chicago venue at the Illinois Institute of Technology.
The program for this year's event will eventually be published on this page.
Details for the evening entertainment (possibly at the Argonne National Laboratory) and recommended beer establishments is still being determined.
If anyone has any questions about the event, please feel free to contact me or the X.Org Foundation board.
The day after XDC2011 ends, it's then onto Munich for Oktoberfest. For the Phoronix readers wondering, in August I will also be at the Desktop Summit in Berlin along with LinuxCon in Vancouver.