Web, privacy and law

Recently, I asked my students if they had heard of linkedin.com. These students are freshmen and they all use Facebook, but they don't really use the web to their advantage. Anyways, when I asked the questions a student answered, "It is a website on which you have a profile that I found when I googled you".... I burst into laughter and so did everyone else. But later when I googled myself to see what showed up, I found that there were a couple of websites posting my information even though I hadn't created an account on them. These are the people finder kind of websites. With technologies like service oriented architecture, AJAX and what not, it's become easy to gather data from a number of websites and put it on yours.... But wait what about my privacy and legal rights??? Don't they say that data gathered for one purpose cannot be used for any other and data should not be accessible to people who don't work with it. So what has changed? How is this working? Just because you have the technology to pull my information from somewhere, doesn't mean you have the right to do that. Can someone suggest me a most recent reading on legal and privacy rights for the Web and Web ethics? Maybe my next research question is right here!!!!