Opt-in e-mail or permission-based marketing has been rightly touted as a means not only of differentiating legitimate direct marketers from low-rent spamsters, but of building stronger customer trust and loyalty. But opt-in, as Luc Vezina of Montreal-based e-mail marketing consulting firm Got Corporation explains, is only the first step in building loyalty. Going beyond opt-in means establishing a reputation for relevance by learning more from the behavior of customers on your list.

Brian Quinn, vice president, advertising, Dow Jones Online, tells us that BT buys now represent up to a quarter of his sales. And yet, he remains careful not to let clients lose sight of the classic value of a media brand, to sell against important content and a valuable audience demo. BT is sweet "icing on the cake" but it isn't the core value proposition for a publisher.

That social networks and user-generated content are the current frontier of online advertising is widely agreed. Yet beyond that consensus, thorny questions abound. Kevin Sladek, CSO of San Francisco-based web video publishing platform developer Video Egg, and Troy Young, Video Egg's CMO, explain that at least part of the answer lies in learning new ways of targeting for the UGC space--something the company is trying to pioneer with its newly launched Video Eggnetwork ad network.

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.

Tom Burgess, CEO of Third Screen, the largest mobile ad network, explains why the menu of mobile behavioral and other targeting options is about to expand dramatically.

It seems years now that we have been talking about the day when search engines will finally fold behavioral profiling into their results and ad serving engines. But search marketers are already taking the first steps toward implementing BT on the back end.