This is an interesting development. (Google Buys DoubleClick for $3.1 Billion - New York Times)
As more and more online services that collect personal information amalgamate, it is important to ask questions about what happens when databases of personal information merge as part of the process. Google already has an advertising network which collects clickstream data, and holds terabytes of personal e-mail, photos, videos and documents. Its social networking site, Orkut, is slowly growing. Doubleclick, on the other hand, has been in the clickstream game longer and is itself no stranger to privacy controversey. (You may recall the fuss raised when it was suggested the DoubleClick may perform data matching with offline personal information.) What's going to happen to the databases?
This bears some close thinking about.