This post explains “if my site was already added by an End-user to their Compatibility View list before my site was updated, and now it’s ready, how would I get the site off of that user’s list? I wanted to share one particular feature that we haven’t blogged about before – the ability to “trim” domains from a user’s Compatibility View list.” End-users also have a way to mitigate compatibility issues they may encounter in the course of normal browsing on sites that do not have the X-UA-Compatible option explicitly set. They can choose to view a site in Compatibility View, an IE7 emulation mode, by toggling a button on the browser’s address bar. Internet Explorer 8 (download) remembers Compatibility Button presses on a per-domain basis in order to provide a more seamless return-visit experience. These domains are stored in a registry location on the client at HKCU\Software\Microsoft\Internet Explorer\Browser Emulation.
Full Article: IE Blog