I think it’s only too perfect to talk about HTML5 using a catch phrase from over 10 years ago. It’ll be dated just as fast. BUT. Right now, it’s super hot, until the next big thing, and I am loving it. I am playing with this theme: http://themeforest.net/item/modernize-flexibility-of-wordpress/1264247 and it’s ah-mazing. It’s responsive so it looks great on my iphone or macbook, but it also has all kinds of cool features, that make me look like a better designer than I am. I think it just shaved two weeks off my project. If you’re shopping themes, do this: search Theme Forest for HTML 5 themes. There are tons. Look at the 5 star ones. Plenty. Go.