Your.Master writes: After weeks of frustrated developers calling for blood, Microsoft has reversed their earlier decision about backwards compatibility. The reasons for doing so are detailed on the latest IE blog entry. Web developers can still explicitly opt-in to IE7 compatibility mode.
Your.Master writes: There's been a lot of fuss about the new IE8 meta tag. After scraping through the comments, it seems apropos to mention some facts about IE8 that were overlooked in previous articles: first, there is a registry setting to force IE8 to always use IE8 standards mode, and far more importantly, future, current unestablished well-formed DOCTYPES, such as the upcoming HTML5, will cause DOCTYPE-switching to IE8 standards mode in IE8. The meta tag is apparently intended to allow opt-in for currently-used DOCTYPEs, and to let future versions of IE know to limit themselves to IE8's capabilities (or to tell IE8+ to use IE7's "standards mode", or quirks mode).