There is also this brief article in Scientific American that comes to similar conclusions (though it also points out that nobody can be absolutely certain):

http://www.sciam.com/blog/60-second-scie...e-ye-2008-12-30

Also, if your are interested, and perhaps only someone in Chris Kavanaugh's field would be, there is also an article on Scientific American's website -- that reports on research that has appeared in the journal Science -- about a North American meteor or comet strike. This strike could be an explanation for the die-off of the Clovis people as well as North American Mega-fauna. Most importantly for me, after reading this article, I can now say "nanodiamonds".

http://www.sciam.com/article.cfm?id=did-a-comet-hit-earth-12900-years-ago