So Google has finally made the leap beyond its stranglehold on contextual advertising into adopting behavioural targeting methods across it's network of publishers who display AdSense ads. Put, extremely simply, if you visit sites concerning baby care information then you should expect to see ads for formula or nappies (OK, diapers) when you eventually click away to another, unrelated site that carries AdSense advertisements CNN.com for example.
As one would expect from the company that "does no harm" (and one whose future is so intinsically linked to the growth of relevant online advertising), Google has covered its bases from a privacy perspective in a way that many of its predecessors failed to do. Users will be aable to see and edit information that Google has gathered about them and anyone - user or publisher will be able to opt out completely of what Google is calling Interest Based Advertising. The ability to edit your profile really is key in that it allows users to choose categories of interest in addition to the inferred interests based on browsing behaviour thus putting control into consumers hands.
The quote below is from a Google blog entry called "Making Ads More Interesting"
"We believe there is real value to seeing ads about the things that interest you. If, for example, you love adventure travel and therefore visit adventure travel sites, Google could show you more ads for activities like hiking trips to Patagonia or African safaris. While interest-based advertising can infer your interest in adventure travel from the websites you visit, you can also choose your favorite categories, or tell us which categories you don't want to see ads for. Interest-based advertising also helps advertisers tailor ads for you based on your previous interactions with them, such as visits to their websites. So if you visit an online sports store, you may later be shown ads on other websites offering you a discount on running shoes during that store's upcoming sale."