So that explains the wedding ring I spotted. From the Palin family:
"We have been blessed with five wonderful children who we love with all our heart and mean everything to us. Our beautiful daughter Bristol came to us with news that as parents we knew would make her grow up faster than we had ever planned. We're proud of Bristol's decision to have her baby and even prouder to become grandparents.
As Bristol faces the responsibilities of adulthood, she knows she has our unconditional love and support. "Bristol and the young man she will marry are going to realize very quickly the difficulties of raising a child, which is why they will have the love and support of our entire family. We ask the media to respect our daughter and Levi's privacy as has always been the tradition of children of candidates."
Now all we need is confirmation from the obstetrician who delivered Sarah's baby, Trig.