This is from the Ansel Adams contest rules.
"Participants, by participating in this Contest, hereby waive and release, and agree to defend, indemnify and hold harmless, Sponsor, SmugMug, Inc., all contest and advertising agencies, and their respective parents, subsidiaries, affiliates, distributors, and all of their respective officers, directors, employees, representatives and agents, and their respective successors and assigns (the “Indemnified Parties”), from and against, any and all rights, claims and causes of action whatsoever that they may have, or which may arise, against any of them for any liability for any matter, cause or thing whatsoever, including but not limited to any injury, loss, damage, whether direct, compensatory, incidental or consequential, to person, including death and property, arising in whole or in part, directly or indirectly, from: their acceptance, possession, use or misuse of the prize in the Contest; or their participation in the Contest; or the use of the Photograph, including without limitation any claims relating to violations of the Content Restrictions."
Not very easy to read, but from what I understand there is simply no claim possible.
As noted above, this is just a reminder that everyone should read the rules and decide whether to submit based on what they feel comfortable with. I don't believe that this is a rights grab (so I agree with Jeff), but rather an agreement not to claim if images are used for any purpose by a very broad group of "Indemnified Parties".