The purse was stolen from a 49-year-old San Anselmo woman who parked her car in the parking lot of the BayMarin Church at 150 N. San Pedro Road around 2 p.m.
The woman told investigators she had left her car door slightly ajar while she was loading items into the vehicle.
When she went inside the church briefly, someone took her purse from between the front seats of her car, sheriff's Sgt. Debra Barry said.
The woman subscribes to Apple's "MobileMe" service, which uses GPS tracking to help find missing iPhones, Barry said.
Deputies used the technology to track the phone to the corner of La Brea Way and North San Pedro Road, where they found 21-year-old Emmanual Krawler of San Venetia, Barry said.
Krawler had the iPhone and $200 in his possession, and the victim's purse was found hidden under a footbridge near Madison and Roosevelt avenues, Barry said.
He was booked into Marin County Jail for possession of stolen property, grand theft, theft with a prior conviction and violation of probation. He is being held on $10,000 bail.
Krawler is on probation for several prior cases including the theft of guitars from a car belonging to another San Venetia resident, Barry said.
He was scheduled to be arraigned this afternoon in Marin County Superior Court.