HTML5 also extends the extends the existing HTML 4.01 tags with new tags for the semantic web, link relations, Microdata, ARIA attributes (for disability accessibility), form field types (range, input validation, etc), audio and video (Apple’s big beef), and Canvas for 2D and 3D SVG/WebGL graphics.
The new CSS extensions include typography enhancements, visuals (columns, textwrapping, rounded corners, etc.) and transitions, animations and transformations (dynamically manipulating DOM elements kinda like some of the JQuery UI features).
All in all this is an amazing and revolutionary toolkit for developing Web applications and will likely lead the way in what and how we develop in the future. A couple of the features (namely Web SQL and Web Sockets) make ne cringe slightly, in that we know that they will be abused, however the potential here is enormous. it’s also interesting to note, that none of the new features are truly revolutionary by themselves, it’s the standardization which is revolutionary.