Privacy is Dead
Privacy is dying. Computers are enabling more processing of data then ever, and the internet helps to collect that information. Government organizations can subpoena this information very easily using the Patriot Act (Essay about the Patriot Act).
We need to be careful what information sites collect about us and what purposes the data can be used for.
It's just to inconvenient to avoid giving out traceable information. You can't use a credit card, much of the internet, E-Z-Pass, a cellphone. All are logged, but for different purposes. Credit cards have to log purchases in order to bill you, but many internet sites track you in order to server relevant information. What's scary is if this information is aggregated or combined. Companies or governments can know everywhere you go if you got a cell phone since they can record the cell phone towers you are near, or possibly even install a GPS tracing program.
Google knows a lot about you, and will know even more once they buy DoubleClick.
Tivo collects aggregated information about your television viewing - but only sells it in aggregate. Online video can be similarly tracked by the people who provide it.
Tracking Cookies can be easily cleared or turned off.
More and more information is public. This has an impact on searches for jobs and such.
Facebook is a good example of a site where you can share your private life with only your friends.
But Facebook also has all of the information. This might not be a problem, but what if they are bought by a company looking to use that data. Facebook has even launched it's social beacon and advertising platform.
Leaks of private information happen pretty often. T.J. Maxx collected more information than was necessary and let its network open for hackers to retrieve the information. Various government agencies have lot laptops containing sensitive information on many employees.
I own a Facebook application called GridView. I have to protect the privacy of our users. Statistics are only released in aggregate, and I attempt to secure our database from being hacked.