Perry gives a sexy over-the-shoulder glance before performing in London. Plus: Lady Gaga, Ashlee, Pete & Bronx, Zac Efron and more

CITY WALK

Taking advantage of the balmy Big Apple weather, Jake Gyllenhaal and a hat-loving Reese Witherspoon – who's been busy training for her role as a pro softball player – step out Saturday for a shopping trip in New York City's SoHo neighborhood.