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
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.
For the gritty details when the metal needs to hit the road, go to the sources to lookup functions, objects, etc and get the latest info on them and their usage.
Implemented standards
Firefox
Internet Explorer
Unsure about Webkit official dev docs (Chrome. Safari) but you can often use the MDC/Gecko docs because they are usually close in standards. (<< Update: Another answer provides Webkit info.)
Standards also act as a good measuring rod for expected behaviour if you face a bug while developing.
This slide show is about HTML 5 standard technologies and must be viewed in HTML 5 (e..g Google Chrome works well).
A Strategy to find more info ...
See this great slide show (using an HTML 5 capable browser - it'll get you in the mood) for the overview...
Then look up the spec you want at the W3C.org website or Google its contents using a search terms to target the site like "site:www.w3.org "html 5" YourTerm" for example the Google Canvas tag.
As far as HTML5 goes, I frequently check out:
And yes, the HTML5 spec, which I recently visited to find out more about supported input types and form field attributes in HTML5:
As for CSS3, I often find myself at:
Safari reference material, which may or may not be HTML5/CSS3 specific:
You can also take a look at HTML5 Laboratory which is my own HTML5 experiment site.
As mentioned above, HTML5 Doctor and Dive into HTML5 are two great resources.