Or they could have an IE6 compatibility mode built into IE8. Then all those companies that designed IE6 apps instead of web apps in the past could specify with a code change that the pages are not www pages but IE6 pages and MSIE could display them appropriately (and addons for FF could use that to hook in an IE6 view, etc.).
The difference between IE6 and IE7 is like the difference between a grain of wheat and risen dough, neither is a loaf of bread [standards compliant browser] but the later is not far off.
