What are the best guides to HTML5 & CSS3 support in web browsers?

Question

Do you know about useful resources about HTML5 & CSS3?

UPDATE:

I\'m (and i think a lot of people) looking for practical information how and to what exten

Answer 1

Believe it or not, wikipedia: comparison of layout engines CSS3 and HTML5 is actually pretty good at very detailed comparisons. Modernizr is very coarse grained.