I lost my iPhone in the back of a cab a few weeks ago, I was very disappointed in myself.
Then my thoughts turned to the populace in New York. What percentage of people would find an iPhone and return it?
50/50 maybe? 60/40 or 40/60?
The girl who found my phone gave it back to me two days later.
My anecdotal evidence suggests that you have a good chance of finding people in New York that are altruistic. Nice feeling.
(Btw a few weeks beforehand I returned a wallet to a girl who left it on the subway, so maybe karma had a hand in my phone finding its way back to me also)