Collecting links for HTML5 resources, let me know if you found other good links as well. Enjoy!
W3Schools
http://www.w3schools.com/html5/default.asp
W3Fool ( An anti-W3Schools campaign )
http://w3fools.com/
HTML5 Glossary
HTML5 - edition for web developers
Sites using HTML5 markup
http://www.html5arena.com
Accessibility
http://www.html5accessibility.com/
The Expressive Web
HTML5 Canvas Tutorials
http://www.html5canvastutorials.com
Can I use
How to order you head section
Html5 headings and accessibility
Juude Blog about HTML5
http://juude.info/html5-layout.php
Best CSS3 Resources
http://www.linkedin.com/news?viewArticle=&articleID=784509223&gid=2071438&type=member&item=71538466&articleURL=http%3A%2F%2Fstylishwebdesigner%2Ecom%2F150-excellent-css3-tutorials-to-make-you-a-stylish-web-designer%2F&urlhash=U0xc&goback=%2Egde_2071438_member_71538466
Efficiently Rendering CSS
Best CSS3 Utilities
http://iroylabs.blogspot.com/2011/09/best-css3-utilities.html
10 Tools to simplify HTML5
http://www.catswhocode.com/blog/10-online-tools-to-simplify-html5-coding
Make old IE to understand HTML5
http://code.google.com/p/html5shiv/
HTML5 Polyfills
https://github.com/Modernizr/Modernizr/wiki/HTML5-Cross-Browser-Polyfills
W3Schools
http://www.w3schools.com/html5/default.asp
W3Fool ( An anti-W3Schools campaign )
http://w3fools.com/
Dive Into HTML5
http://diveintohtml5.org/HTML5 Glossary
HTML5 Rocks
Sites using HTML5 markup
http://www.html5arena.com
Accessibility
http://www.html5accessibility.com/
The Expressive Web
HTML5 Canvas Tutorials
http://www.html5canvastutorials.com
Juude Blog about HTML5
http://juude.info/html5-layout.php
Best CSS3 Resources
http://www.linkedin.com/news?viewArticle=&articleID=784509223&gid=2071438&type=member&item=71538466&articleURL=http%3A%2F%2Fstylishwebdesigner%2Ecom%2F150-excellent-css3-tutorials-to-make-you-a-stylish-web-designer%2F&urlhash=U0xc&goback=%2Egde_2071438_member_71538466
Efficiently Rendering CSS
Best CSS3 Utilities
http://iroylabs.blogspot.com/2011/09/best-css3-utilities.html
10 Tools to simplify HTML5
http://www.catswhocode.com/blog/10-online-tools-to-simplify-html5-coding
Make old IE to understand HTML5
http://code.google.com/p/html5shiv/
HTML5 Polyfills
https://github.com/Modernizr/Modernizr/wiki/HTML5-Cross-Browser-Polyfills