TIN HOUSE has her "Light" up at their site. Y'all know I love me some the free fiction. It starts like this:
The man at the bar on the stool beside her: bent like a hook over some item. A book, not a drink. A children’s book; dog-eared. When he noticed her stare, he grinned and said, “Got a light?”
Here ya go: "Light," which has the very cool bit below:
At a table behind her three women were talking about a new pocket universe. A new diet. A coworker’s new baby: a girl, born with no shadow. This was bad, although, thank God, not as bad as it could have been, a woman—someone called her Caroline—was saying.
A long, lubricated conversation followed about over-the-counter shadows— prosthetics, available in most drugstores, not expensive and reasonably durable. Everyone was in agreement that it was almost impossible to distinguish a prosthetic shadow from a real one.
Caroline and her friends began to talk of babies born with two shadows. Children with two shadows did not grow up happy. They didn’t get on well with other children. You could cut a pair of shadows apart with a pair of crooked scissors, but it wasn’t a permanent solution. By the end of the day the second shadow always grew back, twice as long. If you didn’t bother to cut back the second shadow, then eventually you had twins, one of whom was only slightly realer than the other.