The Duke and Duchess of Cambridge make a grand entrance in London. Plus: Rihanna, Drew Barrymore, Katy Perry and more

SHE'S GOT GUNS!

Who's your new friend, RiRi? Rihanna puts on a hot gun show Thursday at the afterparty for the Hollywood premiere of her upcoming flick Battleship (out May 18), held at L.A's. Nokia Theatre.