UPDATE We now believe we have a full rendering pass (but not necessarily an animation smoothness pass yet). See the bottom of the post for details.
UPDATE The Windows nightly is now available for download. See below for details.
With r31342 WebKit has become the first publicly available rendering engine to achieve 100/100 on Acid3. The final test, test 79, was a brutal torture test of SVG text rendering. Details of the bugs we fixed will follow. Indeed, we found a critical bug in the test itself that would have forced a violation of the SVG 1.1 standard to pass, so until a few hours ago it was not possible to get a valid 100/100. Acid3 test editor Ian Hickson has the details.
Note: this does not indicate a full pass of Acid3. We have a slight glitch in the text rendering that is likely to be fixed soon (patch in progress). Also, the animation is required to be smooth. On typical machines, if you look really closely, you can see a small glitch in the animation on test 26 because 26 is designed to be a performance test. However, we think we are faster than all other browsers on test 26. What constitutes a smooth animation is somewhat subjective.
This is not just a screenshot, you can pull live from SVN and build to see it yourself, and a fresh nightly build is coming soon.
Thanks to our own Dan Bernstein, as of r31356 we believe we have a pixel-perfect match for the reference rendering.
Get the fresh hot bits of the latest Mac and Windows nightly builds which include the full reference rendering pass.
Extra special bonus update: Alp Toker reports that the Gtk port now gets 100/100, although it does not yet match the reference rendering.