Google, DoubleClick Address Privacy Issues
(Seeking Alpha)

“The problem is this: the described relationship between DoubleClick and Google effectively creates an online advertising monopoly.
….
In addition to the imposed monopoly, privacy groups are concerned that Google will simply have too much information on individuals; information that Google never really had permission to have in the first place. Google will literally have access to just about every demographic available about an individual.

Google has responded by announcing that all search-query data will be eliminated after 18-24 months.”