Where there's VC heat there is fire, and as investments started pouring into some behavioral targeting firms earlier this year, financial analysts took note. Marianne Wolk, an analyst at the Susquehanna Financial Group, argues that the rise of BT will affect many aspects of the current online ad ecosystem. Projecting annual BT spending of $5 billion by 2011, Wolk expects this revenue wave to ripple into the search economy as well as alter the leverage content sites exact within ad networks.

The core preoccupation of online targeting thus far has been to scout out from among the millions of active Web users the most likely prospects to pursue. The next step in the pursuit of maximizing ad relevancy, Toby Gabriner, CEO of x+1 argues, is to explore the other half of the targeting equation--identifying and screening out the consumers who don't want to see your ad.

After the Department of Justice subpoenaed search engine records last year and AOL posted search histories just this summer, New York University Assistant Professor and privacy expert Helen Nissenbaum and her colleague Daniel Howe constructed an antidote to search tracking, the TrackMeNot plug-in. Nissenbaum is also working on a book about privacy, so we asked her to explore why search behaviors represent a special case when it comes to online tracking.

What will characterize the next generation of behavioral targeting, Matt Fleckenstein, vice president of personalization technology firm mSpoke, explains, is the ability to generate data and feedback from consumers themselves.

Hartland Ross, president and CEO of eBridge Marketing Solutions, recently tried retargeting the traffic from his Google buys. The results were encouraging, but for now this is not a solution for everyone.