(1) Todd Surovell (UA Anthro PhD, 2003), Holliday, and a cast of thousands published a paper in PNAS:

Todd A. Surovell, Vance T. Holliday, Joseph A. M. Gingerich, Caroline Ketron, C. Vance Haynes, Jr, Ilene Hilman, Daniel P. Wagnerc, Eileen Johnson, and Philippe Claeys, 2009. "An independent evaluation of the Younger Dryas extraterrestrial impact hypothesis" Proceedings of the National Academy of Sciences Early Edition.

The story generated some news buzz including this story in NATURE.
http://www.nature.com/news/2009/091012/full/news.2009.997.html

(2) At the Geological Society of America meetings in Portland this week Holliday's paper on their work in Sonora was presented by Susan Mentzer. That paper and Mentzer's research generated another news story in NATURE.
http://www.nature.com/news/2009/091021/full/news.2009.1034.html

(3) At the recent GSA meetings, Holliday gave another paper that piggy-backed on the paper published in PNAS. That paper "The 12.9ka Impact Hypothesis and North American Paleoindians" (by Holliday and David Meltzer) generated some news buzz as well:
http://news.nationalgeographic.com/news/2009/10/091023-comet-north-america-extinctions_2.html