As an analogy, it would be like UPS opening everyone's packages and cataloging the amount of people who receive which products from Amazon or its competitors. Which products go to which people? How old are the receivers? Are they male or female? UPS would just glean information from private letters to figure this out. They could use this information to mail everyone more appealing advertisements that fit their demographic. Does that make it any less weird that someone is reading our mail? What if UPS was did not cost money and this was their price? Would there be a person in the world who would send a private letter to a spouse through UPS?
As a Googlephile, I've had difficulty with this one. For the BBB, I use Gmail, Blogger, Google.com, iGoogle, and Chrome. They can get lots of information from everything I've made public. They want to sell ads that target me. I understand that. But do they really need to invade confidential emails for marketing info? So far, Google's justifications have been thin. Right now Ireland, and by extension, the EU is investigating privacy concerns. We are most anxious to hear what they have to say. Let's hope all our concerns are laid to rest.