If he is walking past a restaurant where his Facebook friend — say Mr. Rose, the television journalist — was having lunch alone, he could be notified on his cellphone, along with a discount offer for lunch. Mr. Andreessen described this as a win for all parties concerned: a lunch date for Mr. Rose, a discount for himself and a new customer for the restaurant.
Mr. Rose asked whether using that data could make Facebook users feel uncomfortable. Ms. Sandberg said new technology always elicited new anxieties, but that Facebook would have to reassure its users.
“Trust is the cornerstone of our business,” she said.
--Somini Sengupta, NYT, on why I don't share my location information with Facebook