The actress makes a splash at her book signing. Plus: Ashton Kutcher, Paris Hilton and more

SET PEACE

Mark Ruffalo plays nice with the paparazzi last week on the Pasadena, Calif., set of his still-untitled romantic comedy costarring Jennifer Aniston, Kevin Costner and Mena Suvari. The actor is plenty busy these days: He's goes head-to-head as a detective to Tom Cruise's hitman in the thriller Collateral, out Friday.