Microsoft has been on a worldwide campaign to phase out Internet Explorer 6 because of its incredible age; it was released a decade ago. The Internet has changed a lot in the last decade, and the accidental longevity of IE6 has meant that web developers have had to contend with the limitations of the old browser. Because of this, Microsoft has been advertising and encouraging the upgrade to the most modern browser for your platform: IE8 for Windows XP or IE9 for Vista and better. Unfortunately, where there has been some progress made, it hasn't been great. In fact, as of writing, 8.3% of the world still uses IE6. That is a frightening number.
Microsoft has finally decided to go a little militant on IE6 (and IE7) by adding Internet Explorer updates to the critical list on Windows Update. They have also retired the need for IE upgrades to be interacted with (such as hitting next 10 times before IE8 will install on XP). Over the next few months, any computer running Windows Update will automatically be upgraded to the most modern version of the browser for their computer.
This leaves Apple's Safari as the only major browser to not automatically update itself in the background without any input from the user. This is a feature that all IT and software professionals have been wanting for ages now. Supporting antique browsers means tremendous amounts of work for both sides of the computer industry. IT has to worry about a decade worth of security flaws and holes that have remained open because users will not upgrade. Web developers have to go through major tricks to make older browsers still run more modern websites. Some sites, such as Google and WordPress, have dropped support for the old browsers entirely already, informing their customers that if they want to use the software, they need to upgrade.
Of course, if you like running on the cutting edge of 20th Century technology, you do have the ability to opt-out of the upgrade, but we suspect very few people will do this. If you are still running IE6, it is probably because you don't know how to interact with a dialog box, so going into Windows Update scheduled settings and turning off automatic updates is probably not going to happen.