WILLIAMSTOWN, Mass. — The Seattle Art Museum and the Clark Art Institute in Williamstown, Massachusetts, are wagering valuable pieces of artwork on Sunday's Super Bowl.No, the loser won't give away a masterpiece — just a three-month loan. All shipping and expenses will also be paid by the losing museum.If the New England Patriots win, the Seattle museum will loan Albert Bierstadt's 1870 landscape, "Puget Sound on the Pacific Coast" to the Clark.