A List Apart: Articles: They Shoot Browsers, Don't They?
This is gobsmackingly audacious. Imagine a new version of Word that behaves exactly like the old version of Word unless the document it is processing contains a hidden instruction to unlock any new features. That's what Microsoft is demanding that web developers implement. Unless you explicitly say otherwise, IE8 (and IE9 and IE10, ad infinitum) will behave exactly like IE7.