From the Press Release:
Free Public Access on Ancestry.com
To commemorate the NARA-Ancestry.com agreement on the eve of Memorial Day, Ancestry.com is making its entire U.S. Military Collection — the largest online collection of American military records — available for free to the public. From May 20 through May 31, people can log on to
http://www.ancestry.com/military
to view more than 100 million names and 700 titles and databases of military records, the majority of which come from NARA, from all 50 U.S. states.