Here's something else of interest: It was less than two years ago that as saying that Google chose not to participate in behavioral targeting "for a variety of reasons," noting that the company was "very careful" about "traditional behavioral targeting."

Privacy Concerns

Privacy advocates are already at the change. The Electronic Privacy Information Center (EPIC) calls the move a "disaster" and has asked the U.S. Federal Trade Commission to intervene. The Center for Digital Democracy (CDD), meanwhile, is asking Google to leave users opted out of the program by default, then allow them to opt in if they so choose.

Google representatives downplayed the need for such an idea, insisting that the majority of users would "prefer to see more relevant advertising." Oh, yeah -- there was one other teensy little consideration, too:

"Offering advertising on an opt-in basis goes against the economic model of the Internet," Google spokesperson Christine Chen told the IDG News Service, operated by PC World parent company IDG.