Since the announcement of the Schema.org standards for microdata back in the summer of 2011, I have wanted to incorporate the new conventions into WordPress. At first I considered writing a plugin that would add information dynamically, but this didn’t seem to be a very efficient route. Instead, I have decided to extend the default Twenty Eleven theme that is already gorgeous and well-defined, and create a child theme that builds the microdata standard directly into the template.
Adding microdata to your site has several benefits. First and foremost, you contribute to machine readable data everywhere. The Internet is a wonderful place for humans to browse, but we can make it more accessible and more consumable if we let the computer figure as much of it out as it can. Second, search engines can use this data to get a better understanding of each page that it indexes, and hopefully provide more relevant search results. (Notice that I am not saying you are going to get an SEO boost for doing this. You may, you may not, I have no idea. But if everyone included this data on their sites, the results would be better.) There are no downsides really to simply plugging the data in.
If you are using Twenty Eleven as your theme and would like to add Schema.org microdata to your site without any effort on your part, give this child theme a try. You can download it for now from my Twenty Eleven Schema.org Child Theme page. Eventually I hope to add it to the WordPress Theme repository, but it needs some testing before it’s ready to head over there.
Hope it helps!