GREY'S ANATOMY - "Now or Never" - Drs. Cristina Yang, Meredith Grey and Alex Karev respond to the news that Dr. George O'Malley has joined the U.S. Army, on "Grey's Anatomy," THURSDAY, MAY 14 (9:00-11:00 p.m., ET) on the ABC Television Network. SANDRA OH, ELLEN POMPEO, JUSTIN CHAMBERS