Smile, Opera passes the Acid2 test! The above screenshot is from build 8249 (compare to the reference rendering), where we fixed a problem with the stacking order of floated and inline elements. According to the Elaborate description of Stacking Contexts in the CSS2.1 spec., floated elements are supposed to be under inline elements, though Opera painted them on top. This caused two problems in rows 4 and 5: the eyes were dimmed and there was a red bar to the right of the eyes. Check this test case to see how your browser handles it.
This last change had caused some regressions in the rendering engine, but they should all be cleared up by now. Also, since Opera 9 is still under development, there's a possibility that there could be further regressions in the rendering engine that could cause a weekly build not to pass the test. We don't expect this to be the case, though.
For an overview of the fixes we've done to get Acid2 working in Opera, have a look at http://weblog.timaltman.com/category/opera/acid2/. You can also compare screenshots by visiting http://timaltman.com/acid2/. If you're using Opera, simply press Space repeatedly to view each screenshot after navigating to that directory.
Want to test Acid2 in Opera yourself? Download the latest weekly build from the Opera Desktop Team blog!