Safari continues to stay cutting edge, thanks to David Hyatt's work to make Safari the first browser to pass the Web Standard's Project's Acid2 Test. And while not part of the current release in Mac OS X 10.3.9 or the about to be available for the world Mac Os X 10.4, these changes are sure to be a part of a future release in short order.
Being fully standards compliant is extremely important in this age, there are so many browsers, so many web sites, that without standards, it would all be a royal mess. Internet Explorer is no longer the de facto standard, and has for years failed to be standards compliant as the internet evolved. Microsoft is now paying the price for that, as are web designers that catered to IE's flaws. Cute graphics on web sites claiming that the site looks best when viewed with IE or that require IE for certain features are no longer a badge of honor, but a warning label that the web designer failed to code properly, used obsolete tools, or just plain didn't care enough about their target audience to create a site that was browser independent, something that can no longer be done in this modern age.