The software industry has been evolving our understanding of privacy, as society's understanding and expectations around privacy have evolved.
I remember having a class around privacy and data protection in college, ten years ago. In those days, in Argentina at least, much of the body of laws that governed personal data were "transferred" over from paper-based systems. Certainly the principles still applied around data ownership and rights over one's personal data, but there was a lot less in terms of accepted policies and practices, and a lot fewer ways in which data could be gathered.
Today we're recognizing International Data Privacy Day, and there are a number of resources made available to developers and end-users on the subject. You can see some recent research on the current state of location-based services, for example.
I strongly recommend taking a look at the 'Resources' section on the bottom-right to find out some interesting ways in which you might be revealing more information than you're comfortable with - I know I got some food for thought out of it.