Also, if you have automatic updates turned off, IE will not automatically update. You would have to allow the update when you manually update on the MS update site. They've also committed to making opt-out mechanisms for enterprises:
Microsoft to begin automatic Internet Explorer upgrades in 2012Ed Bott report.
By Ed Bott | December 15, 2011, 5:00am PST
Summary: In a major policy change, Microsoft plans to deliver IE upgrades automatically to Windows users. That moves IE incrementally closer to its fast-paced competitors, although there are still enough exceptions to keep enterprise users happy.
In January 2012, Microsoft will begin installing the latest version of Internet Explorer on Windows PCs automatically, via Windows Update.
Automatic browser updates will begin rolling out worldwide in Australia and Brazil and will gradually scale up to additional countries and continents over time. Customers running Windows 7 and Windows Vista will be updated to Internet Explorer 9. Those who are using Windows XP will get Internet Explorer 8—the highest version available for that platform.
The new policy represents a major change for Redmond, which currently classifies new browser versions as Important updates but requires the user to manually consent before installing an upgraded version.
With this change, Microsoft joins Google and Firefox, both of which currently push out automatic updates to all users. The big difference is that Microsoft will continue to support older versions of browsers. That’s a crucial distinction for enterprise customers, who need to test and approve any new software release before deploying it and who have complained loudly about Mozilla’s decision to drop support for all but the most recent browser version with their new rapid-release cadence.
Multiple opt-out mechanisms will be available for businesses and consumers who choose not to upgrade:
•If you previously refused an update to IE, you will not be automatically updated.
•As is the case today, you’ll be able to uninstall an Internet Explorer update and roll back to the browser that came with your Windows version.
•Enterprises can block the automatic installation of IE updates using Microsoft’s Blocker Toolkit for IE8 and for IE9.
•Microsoft has committed to making opt-out mechanisms available for future IE releases as well.