A: Everything, lately.
With yesterday's 10.4.11 update, Safari for Windows update and, of course, lots of people upgrading to Leopard, most Safari users will be on the Webkit 3 platform. To celebrate, Ars points us to the Surfin' Safari Weblog's top 10 new things in WebKit 3 (the open source basis for Safari). They basically boil down to speed improvements and added features.
To paraphrase:
1. Enhanced Rich Text Editing
2. Faster JavaScript and DOM
3. Faster Page Loading
4. SVG
5. XPath
6. New and Improved XML Technologies
7. Styleable Form Controls
8. Advanced CSS Styling
9. Reduced Me
