Despite rumors of a split, Ryan Phillippe and Amanda Seyfried “were all over each other and making out all night” at Madonna‘s post-Oscar party, even though his ex-wife Reese Witherspoon was also there with her new fiancé, Jim Toth, a spy tells us. Also at Guy Oseary‘s Coldwater Canyon mansion was pregnant Natalie Portman, who was “dancing and had a great time until the early hours,” plus Colin Firth, who “celebrated so much that he started slurring.” The bash, which went on until 5 a.m., drew Mick Jagger, Tom Hanks, Gerard Butler with a brunette beauty, Sean Penn, Scarlett Johansson, Ralph Fiennes, Mila Kunis, Cameron Diaz, Gwyneth Paltrow, and Bradley Cooper and Renée Zellweger, who “looked cute together dancing.” Our source said, “Madonna and her dancers put on a show for everyone. Cameras were banned, and guests were ordered to leave their bodyguards in the security tent.”