ADMIXTOOLS (Patterson et al. 2012) is a software package that supports formal tests of whether admixture occurred, and makes it possible to infer admixture proportions and dates. It can be downloaded for LINUX (see documentation). The software package also includes Affymetrix Human Origins Curated Dataset. Write to Arti Tandon if you have questions about the software and for scientific questions write to Nick Patterson. The new release fixes a serious bug in qpDstat.I've used this software before and posted some D-statistics from it on the blog, so if you find any that look strange, feel free to leave a comment. In any case, I'll be using the new version of qpDstat from now on.
UPDATE (Feb 22): Nick Patterson asked me to post the following for users of ADMIXTOOLS:
Choongwon Jeong of the University of Chicago found a serious bug in qpDstat (computes D-statistics) that sometimes returns D with an incorrect sign. If you use the program please download ADMIXTOOLS version 1.1 from the Reich lab web page. http://genetics.med.harvard.edu/reich/Reich_Lab/Software.html