For those of you that don't know, Safari is Mac's browser, and if features cutting edge technology, just like FireFox 2 and Internet Explorer 7, but unlike them it feature's Mac's "branding". For Safari, that means the clear, "plastic" button renderings for form elements, and the clear and blue plastic looking scroll bars.
I've previously been of the mind that these features were kind of gimmicky, I mean making the buttons look different doesn't really make the system any better, just different. Besides that, as a designer, it means I loose control over what my buttons look like, at least to a certain extent... but after using S3, I'm hooked. I like the look of them.
Still not buying a Mac though.