Google has done a good job with determining what is and what is not boilerplate using algorithms. What this means is there is generally no need to correctly annotate what content is boilerplate and what is not. Whether the on-page words are part of the navigation, the footer, or some sort of sidebar, generally using microformats is not necessary. That said, it is not unhelpful.
While Google can do a good job figuring out what is what on a page, for those who have control of their on-site content and are interested in standards, Google lists microformats that it uses in determining boiler plate content. Depending on what kind of content you have on your site, microformats can enhance and hasten Google’s indexing of boiler plate content. Additionally, using Google’s webmaster tools can help a webmaster determine whether or not Google is handling the content on the site correctly or whether it is mistaking it for duplicate or low quality content.