Google has added new documentation to their Structured Data section in Google Developers for breadcrumbs support. Breadcrumbs enable potential visitors to see the page’s hierarchy in the Google search results, and also provides an additional context clue to help a searcher decide if the page likely has what they are looking for.
With Google putting more emphasis on breadcrumbs in the search results, especially for mobile, it makes sense that webmasters should take advantage of the mark up for breadcrumbs to add it to their site.
You can find the markup information here.
And in case you are wondering, according to Gary Illyes, there are no plans to make the breadcrumbs clickable.
@DeanCruddace I'm not aware of such plans.
— Gary Illyes (@methode) June 15, 2015