After the Internet Explorer 8 team posted a detailed update on its plans for new privacy features, most of the comments on the team blog and around the Web have seemed to focus on which of these capabilities are or aren't already available in other browers, like Firefox. Which makes me wonder why Firefox doesn't have a bigger market share and user base, what with that jump on the "porn mode" option in plug-in form, but that's a question for another day. A different possible effect of these IE8 features piqued my interest.

The combination of several user options is expected to bring more ad blocking and browser user-data-gathering configurations to privacy-protecting surfers. InPrivate Browsing lets users turn on and off an ongoing record of cookies and history. Delete Browsing History lets users go back and perform similar actions after visiting Web sites. InPrivate Blocking helps users stop cross-site tracking -- and easily see which sites are attempting it. And InPrivate Subscriptions will be an extension of Blocking, in that users can select to subscribe to sites' published lists of types of content to automatically block.

The vice president of the Interactive Advertising Bureau, Mike Zaneis, is being widely quoted as saying that this set of changes to IE, "has the potential to undermine the economies of the Internet." It isn't quite clear whether Zaneis and other worriers fear that some ads will be blocked (though Microsoft says that's not the intent and has apparently provided some sort of test that shows ads coming through just fine at this point), or whether they fear more that the "third-party" tracking has been targeted for zapping.

Either way, I'm wondering what the reaction is among Microsoft ad sales teams, especially in light of another announcement from yesterday. I'm thinking those guys are feeling a bit put out. ComScore reports that in June, Microsoft was the top display advertiser online, with 5.5 billion display ad views. That equates to 1.7 percent of total display ad views for the month. Just think what it could be with a Yahoo acquisition and no IE8 ad blocking...