see http://www.nychinaren.com/f/page_viewtopic/t_33462.html

If you find an iphone, you'd better leave it to costco. Iphone has a function of "Find my phone". They will find you. But they usually will not go to your place to pick it up because they feel it is dangerous (e.g. some criminals). I knew a friend who lost her iphone and she asked the police officer to go search it.