HTML 5 Specifications current as of April 27, 2011 (the day this blog is posted) can be found at:

If you are trying to stay ahead of the curve with respect to the current web technology, please take a look at this specification.

You might be saying: HTML5!  I see infinite possibilities and I am not tied to any technology.  Good point, but consider all of the people who have to maintain your application in that infinite future. 

Some of the questions you might be thinking about:

1. What about HTML 5 versus XHTML

http://www.w3.org/TR/html5/introduction.html#compliance-with-other-specifications 

2. A good introduction to HTML

http://www.w3.org/TR/html5/introduction.html#a-quick-introduction-to-html

 

Have fun getting ahead of the curve, make sure to review and read the changes over the next few months!