Judging from these photos, Kate Beckinsale either left the salon before her pedicurist was finished or she has some new fangled "French" pedicure in which the toenail is painted white and then a thin layer of black polish is applied all the way around the perimeter to simulate the look of an unwashed foot. Very nostalgie de la boue with a twist, given that these particular shoes cost upwards of $500. Also, her toes are falling off the sides of the shoes.
And while we're on the subject of shoes let me just say: Don't try this at home:
No one loves strappy high-heeled sandals more than me, but the thong strap and the high heel don't mix. One slightly false step and you've got a broken toe. Trust me in this matter.