Google will be indexing microdata in websites. I'd like to find out which cms's (if any) will allow custom microdata output for WYSIWYG editors or insertion of microdata to user generated content.
I don't think it is hyperbole to say that HTML5 will change the way that you think about web development. I welcome many of the changes as they make development easier, and the user experience richer. With any change, though, there is certain to be a bit of trepidation and controversy. One addition that certainly is not without its controversy is the Microdata specification, but I believe the benefits of this very simple specification are going to change how you look at your mark-up in the very near future.