You can find a growing series of in depth articles on CSS3 and HTML5 features at Web Directions, the site associated with our (pretty awesome) conferences for web designers and developers. Articles include
- The DOM Selectors API
- CSS3 Transitions and Animations
- HTML5 Video and Audio
- CSS3 Radial Gradients
- CSS3 Linear Gradients
- Offline web sites and apps with HTML5 appcache
You might also like to take a look at:
- Style Master, our CSS editing tool, with great CSS3 support
- John's video based, 15 lesson CSS3 course, and 11 lesson, video based HTML5 Course at Learnable
- John's Developing with Web Standards, which covers CSS3 (and HTML5) as well as HTML, CSS, the DOM and more in detail
For details on current browswer support of CSS3, HTML5 and other new fangled web technologies, see When Can I use...