The people who develops Opera and WebKit are racing to pass Acid3 test. Both camps have scored 100/100 on Acid3 test. According to both Opera and WebKit camp, even though they scored 100/100, there are still some bug fixing to do.
The WebKit folks announces that WebKit achieves Acid3 100/100 in public build, today.
With r31342 WebKit has become the first publicly available rendering engine to achieve 100/100 on Acid3.
Meanwhile, Opera folks were the first to claim perfect score on Acid3 test using their internal build.
I downloaded WebKit build r31344 and ran Acid3 test on it. The video can be found here (QuickTime Movie 744KB).
WebKit is available for Mac OS X and Windows.