There are some great resources on the net to learn more about HTML5 and CSS3 here is just a list of a few I find really helpful:

  1. The MSDN IE9 feature guide shows you what's supported in IE9 and how you can develop for it.
  2. Getting started with CSS3
  3. CSS Portal
  4. The Opera software Dev Site
  5. HTML5 Doctor
  6. HTML5 Rocks
  7. Dive into HTML5