iPhone OS 3.0 Safari scored 97 out of 100 in Acid3 Test. The newly seeded iPhone OS 3.1 beta (build 7c97d) includes a tweaked version of Safari that scores 100 out of 100 in Acid3 Test. Even though Safari scored 100, it still did not render the page identically to the reference page. Note the white X in the pink box on the top right corner of the test box.
Meanwhile, iPhone OS 3.1 beta Safari did not even pass Acid2 Test.