I was shocked a bit to hear this, since Google has said time and time again that rich snippets and structured markup doesn't help your site rank higher in Google. But that might change in the future.
John said that "over time, I think it [structured markup] is something that might go into the rankings as well." He added his rational:
If we can recognize someone is looking for a car, we can say oh well, we have these pages that are marked up with structured data for a car, so probably they are pretty useful in that regard. We don’t have to guess if this page is about a car.
John Mueller, while not in charge of Google's ranking algorithms, does have insight into what Google is thinking on that front added that "definitely makes sense to use structured data" for ranking in those situations. He said:
So I think in the long run, it definitely makes sense to use structured data where you see that as being reasonable on the web site. But I would’t assume that using structured data markup with make your site jump up in rankings automatically. So we try to distinguish between a site that is done technically well and a site that actually has good content.
Just because it is done technically well, it doesn’t mean it is as relevant to the users as content that is not done as technically well.
Watch the video below, feel free to skip back to where the question starts but I started at where John said they may use it in the future:
Forum discussion at Google+.