In 2011, Google teamed up with Microsoft and Yahoo to launch schema.org, an initiative to support a common set of schemas for structured data markup. You might wonder whether or not implementing these schemas may influence your ranking in Google (or the other search engines, for that matter).
Google's Matt Cutts posted a new Webmaster Help video talking about this, responding to a user-submitted question:
I know rich snippets can increase CTR for my mention on a SERP. But is the use of schema.org code beneficial for my actual positions on the SERPs as well?
"On one hand, I wouldn't necessarily count on that....Just because you implement schema.org doesn't mean you necessarily rank higher. But there are some corner cases like if you were to type in 'lasagna,' and then click over on the left-hand side and click on 'recipes,' that's the sort of thing where using schema.org markup might help, because then you're more likely to be showing up in that at all. So there are some cases where it can be helpful to use schema.org markup."
"I wouldn't necessarily count on that giving you any sort of ranking boost...I'm not going to take it off the table, but for example, it might make sense in some of those specific topic areas, but just because somebody implements schema.org markup, that doesn't mean that they're necessarily and automatically a better site, so I wouldn't count on that giving you a good ranking boost, although it can be a good idea to markup things in a rich structure just because, you know, then different people can slice and dice and find your site more easily if they are doing more digging."
Let's put it this way: it seems unlikely that it will hurt your rankings.