Mischa Barton shopping downtown before heading to the gym ... Catherine Zeta-Jones crossing the street on the Upper East Side ... Christina Milian leaving her hotel ... Hugh Jackman walking daughter Ava to school ... Matthew McConaughey and Camila Alves arriving at JFK ... Will Ferrell and Mark Wahlberg hanging out on the set of The Other Guys ... Michelle Williams walking daughter Matilda to school ... the singer Monica sitting in an SUV outside her hotel in Midtown ... Shakira standing in front of the Plaza Hotel ... and Sienna Miller walking her dog downtown.