Yesterday, Microsoft unveiled to the world its Windows 8 Release Preview. The release will be the last before Microsoft ships Windows 8 later this year.

The Release Preview contained plenty for industry observers and the curious to digest. There are performance improvements, more apps, better support for multiple monitors and so on and so forth.

Bundled with Windows 8 is Internet Explorer 10, the newest version of Microsoft’s web browser. Microsoft believes it’s the best, most capable version of its often-criticized browser software ever, and it might also prove to be be the most controversial, but not for the reasons you might guess.

Why’s that? Microsoft announced yesterday that, by default, IE10 will ship with a ‘Do Not Track’ feature turned on.

“We believe that consumers should have more control over how information about their online behavior is tracked, shared and used,” Microsoft’s Chief Privacy Officer Brendon Lynch wrote. “Of course, we hope that many consumers will see this value and make a conscious choice to share information in order to receive more personalized ad content. For us, that is the key distinction,” he added.

As Wired’s Ryan Singel notes, Microsoft’s move could be a blow to the online advertising industry, which has sought to promote privacy legislation that doesn’t restrict the ability of ad companies to collect personal data too greatly, “Consider this scenario: If indeed the net’s major advertisers obeyed Do Not Track and IE 10 keeps the default,  more than a quarter of the net’s users would be opted out of behavioral ad tracking by default,” Singel writes.

Microsoft’s announcement comes at a time when plenty of companies are grappling with privacy-related issues. In Europe, of course, the new EU cookie law has created plenty of headaches for publishers and advertising firms alike as they rush to implement solutions that may or may not be compliant. It’s so bad that EU institutions apparently can’t even deal with the law.

Interestingly, if more browser makers follow in Microsoft’s footsteps and turn ‘Do Not Track’ functionality by default, it could render the EU’s approach to this thorny issue moot. After all, if most browsers support ‘Do Not Track’ and publishers (by choice or by force) respect ‘Do Not Track’ preferences, the requirements of the EU cookie law would arguably for all intents and purposes be useless.

Of course, we’re not there yet and it remains to be seen how the privacy wars will play out. But one thing is for sure: in the drive to ‘protect privacy’, things are going to get a lot more confusing, costly and inconvenient for publishers, advertisers and, sadly, the very people everyone says they’re trying to protect — consumers.