Google and other companies have replied to inquiries by the U.S.A. House Energy and Commerce Committee about tracking personal information and behavior to serve advertisements.

Google's reply: http://energycommerce.house.gov/Press_110/Responses%20to%20080108%20TI%20Letter/110-ltr.080108responseGoogle.pdf (pdf)
List of other replies: http://energycommerce.house.gov/Press_110/080108.ResponsesDataCollectionLetter.shtml

Ellen Nakashima of The Washington Post wrote a story about this.
http://www.washingtonpost.com/wp-dyn/content/article/2008/08/11/AR2008081102270_pf.html