Today Microsoft released 2 out-of-band security updates:
Everyone should get the update for Internet Explorer. Developers should also get the update for Visual Studio.
For more information see Microsoft Security Advisory 973882, Microsoft Security Bulletins MS09-034 and MS09-035 Released, a post on the the Microsoft Security Response Center (MSRC) blog.
If you have automatic updating turned on, you may already have the updates. To learn how to turn on automatic updating for your operating system, see Update your PC automatically.
If you do not have automatic updating turned on, or to check whether you need the updates, go to Microsoft Update.
What is an out-of-band security update?
An out-of-band security update is an update that is released outside of the normal Microsoft security update schedule. Microsoft normally releases updates on the second Tuesday of the month.