In what could have major repercussions for the business of online marketing, Wired’s Ryan Singel reports Microsoft is making so-called “do not track” service default in the latest version of its browser Internet Explorer:

Microsoft announced Thursday that the next version of its browser, IE 10, will ship with the controversial “Do Not Track” feature turned on by default, a first among major browsers, creating a potential threat to online advertising giants.

That includes one of Microsoft’s chief rivals — Google.

The change could also threaten the still-nascent privacy standard, and prompt an ad industry revolt against it.

Given the titans involved — and Internet Explorers’s use — this could get real ugly real fast.