Safari 4 has been out for a week or more now and you eigther love it or you have gone back to Firefox at this point. The one thing not mentioned much is that Safari 4 supports HTML5 and CSS3. HTML 5 now allows support for audio and video tags, which in turn allows much easier video and audio integration into ones website. CSS 3 is also being supported by the browser which allows dynamic shadows and reflections within the browser itself. Lets hope Apple touches more on this during the March 24th event.
For an example of HTML5 and CSS3, see Apple’s very quick demo [here]