According a blog post in MSDN by Dean Hachamovitch, General Manager of Microsoft's Internet Explorer team, Internet Explorer 8.0 has passed Acid2 test for browser compliance with HTML and CSS.
Acid2 employs certain features of HTML and CSS. The purpose of employing such features is to highlight the problems with browsers that do not display it correctly. The Acid2 test should render correctly on any browser that follows the W3C HTML and CSS 2.0 specifications. Any browser which does not correctly and completely support all of the features which Acid2 uses will not render the page correctly. Because Acid2 tests how web browsers deal with faulty code, the test is intentionally not written to W3C CSS standard specifications, and fails validation.
The first beta of IE8 is expected to come in the first half of calendar 2008.