Microsoft released the IE 8 will be distributed via Automatic Updates (Windows Update).
The update will be classified from different fomras depending on the version of the system used:

• In Windows XP and Server 2003, IE 8 will be classified as a high priority update;
• In Windows Vista and Server 2008, IE 8 will be classified as an important update;
• In the other versions, IE 8 will be classified as a top priority update.

As in IE version 7, some companies are expected (Google), are manifested by the fact that Microsoft includes the browser in Windows updates.
But anyway, just waiting to see.

If you do not want to receive IE 8, install the lock tool released by Microsoft to reject the update package.

Source: Winhelp