Safari has just become the first released browers to pass the Acid 2 test. Acid 2 is a complex HTML, CSS and PNG layout that was created to test the standards compliance of browsers for some of the latest Web Standards. The word is that Opera will not be far behind and other KHTML/WebKit based browsers like Konqueror will soon pass as well. (WebKit is a Mac OS X framework for displayign HTML based on the Open Source KHTML project originally produced by the KDE team. Web Kit and KHTML, after a rocky start, share a lot of code and patches.)
This kind of standards support is great news for the Web and web developers. Standards support allows for developers to create sites more easily (and thus more cheaply). Standards based Web development can reduce the amount ot HTML, reducing the size of pages, which makes downloads faster, and lowers the bills on web hosting for the site owners. Hopefully it will be followed by wider support when IE 7 is released. Firefox/Mozilla already have really good standards support and they will certainly catch up to Safari very soon.