To clarify the situation, I asked Chris Wilson what would happen if IE8 were to encounter a valid, well-formed document with a strict DOCTYPE. My worst fears were realized when he confirmed that the browser would behave exactly as if it were its predecessor.

...Instead of asking that developers who want to opt out of future improvements do so with the addition of a meta element or header, Internet Explorer expects standards-savvy developers to actively opt out of version targeting? by using version targeting.

The reasoning here is that less savvy developers shouldn?t have to worry their little heads about adding one extra line to their documents. Instead, they should be encouraged to continue to write to the quirks of one specific browser version from the market leader. That their documents will ?break? in other browsers is not Microsoft?s problem...