In the rather rarefied atmosphere of web standards compliance, the Acid3 suite of browser tests is like a pro wrestler's chair to the back of the head: if you can take it and keep standing, that's very impressive. The Acid3 suite, first released at the beginning of this month, pushes browsers to the very edges of their rendering, SVG, CSS and DOM scripting capabilities -- all necessary for a consistent and interoperable Web 2.0 experience.
As with the earlier Acid2 test, there's been a bit of a horserace among browser development teams to be the first to the finish line with Acid3, including the WebKit squad responsible for Safari's underlying engine; Acid3 dev Ian Hickson gives major props to Apple and the WebKit devs on his blog, including efforts to clear bugs in the test suite itself (he had to work quite hard to find standards compliance issues in WebKit). On Wednesday evening, both the Opera and WebKit teams declared a 100% score -- not a full pass, as there are minor issues to clean up, but nevertheless the test looks like it should. With the Mac nightly build of WebKit available for download, you too can feel the power of this fully operational web standards battle station.
[A quick clarification: While both Opera and WebKit have claimed 100% on Acid3, only one of the browsers -- WebKit -- has a publicly downloadable version right now that can make that score. Opera's build won't be released for another week or so.]