The Safari browser passed the Acide3 test with 95/100. The WebKit team has fixed an exceptions, and now they match the DOM 3 specification.
I think the browsers must to match this specification at the top level, because it will be interesting to develope more web apps. Nowadays if you're developing a Web page you need view correctly in the most browsers and it's very hard try and solve the problems.
And congratulations to the WebKit Team.
Vía WebKit Blog.