Caught in the Act!

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• New mom Ali Larter showed off her svelte post-baby body in black workout leggings and a matching top during a trip to the Hollywood post office with her hubby Hayes MacArthur and 6-week-old Theodore. "They were that loving family that you couldn't help noticing," an onlooker tells us, adding that Larter was singing to her son and rocking him back and forth. Says the onlooker: "When she looked down again at the baby, her face would just explode into a smile."

• Leighton Meester, celebrating her Nylon magazine cover in style at the W Hotel Downtown in N.Y.C. The Gossip Girl star was joined by pals like Kanye West, who traded numbers with Jessica Szohr, and her The Roommate costar Minka Kelly. Meester sipped beer while other partygoers drank wine and champagne.

• Leonardo DiCaprio, stopping into Voyeur in L.A. for a drink with Gerard Butler. The actor grabbed his usual table with a bird's-eye view of the clubgoers. DiCaprio got comfortable right away, propping up his feet on the table, while Butler seemed interested in scoping out the female clubgoers. And girls were swarming around their table for a chance to look at the guys up close.

• Lisa Marie Presley, celebrating her 43rd birthday at Tao in Las Vegas. She was joined by her hubby Michael Lockwood, mom Priscilla, daughter Riley and Ryan Cabrera, among others. The group of 40 enjoyed a meal of the restaurant's signature items and surprised Presley with a birthday cake at the end of the meal.

• By REAGAN ALEXANDER, JENNIFER GARCIA, LINDSEY GILBERT and MARK GRAY

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