Microsoft plan for "Do Not Track" by default
With the increasing role the internet plays in our lives, and the increasing value in behaviourally targeted advertising, campaigners have become increasingly vocal about the resultant privacy issues. The EU Cookie Directive was one response to these concerns, and in 2009 a related standard was proposed - the "Do Not Track" header. "Do Not Track" outlines a standard way for web browsers to indicate that the user does not wish to have their behaviour and usage of websites tracked - arguably a more efficient solution than requiring every website to implement a user interface for privacy controls independently. The "Do Not Track" header is currently supported by all major browsers, with the exception of Internet Explorer 8 and below - meaning it's supported by around 80% of web traffic - but it should be noted that unlike the Cookie Directive there is currently no legislative force behind the proposal. It's up to advertisers and websites whether they take account of the header and what actions they take as a result, and currently relatively few do (although the Federal Trade Commission - one of the groups backing the proposal - have indicated that they are hopeful that this will change within the year).
So far "Do Not Track" has been implemented solely as an explicit opt in choice, hidden away in browser settings menus and generally untouched by users unaware of its existence. At the end of May Microsoft announced that the next version of Internet Explorer will ship with the "Do Not Track" option enabled by default. This lead to a significant backlash from the members of the advertising industry, who had agreed to abide by "Do Not Track" only if it were an opt-in choice, and concerns that enabling "Do Not Track" by default would dilute the explicit nature of the header to the point where it was essentially meaningless. Mozilla have dismissed the idea of enabling "Do Not Track" by default, stating that it should express the user's view, not the browser vendor's - "For DNT to be effective, it must actually represent the user’s voice."
In the last few days members of the W3C - the group developing the standard, of which Microsoft are a member - have announced a "compromise proposal", which would explicitly forbid IE10 from shipping with an opt-out "Do Not Track" setting while still being compliant with the standard, essentially allowing websites to ignore the header where IE10 is concerned. Microsoft have said they will fight against this change, but it seems prevailing opinion is against them.