GREY'S ANATOMY - "What a Difference a Day Makes" - Geogrge gives his best friend, Izzie, away to be married, on "Grey's Anatomy," THURSDAY, MAY 7 (9:00-10:02 p.m., ET) on the ABC Television Network. SANDRA OH, KATHERINE HEIGL, MICKEY MAXWELL, T.R. KNIGHT, JUSTIN CHAMBERS, ELLEN POMPEO