It's Ellen's Memorial Day show! Ellen is pulling out all the stops with an incredible performance from "So You Think You Can Dance"! MEREDITH VIEIRA is here in her final days as host of the "Today" show. She'll tell Ellen all about why she decided... (more) to make the career change. And TAYLOR SWIFT gives an unforgettable performance of her hit song "Mean," from her new album, "Speak Now."