In the latest Google Webmaster Help video published on YouTube today, Google's Head of Webspam, Matt Cutts addressed the following common question:
"Does the use of schema.org markup create a ranking benefit?"
Matt explains that the simple inclusion of schema.org markup on a website will not necessarily provide a ranking benefit for that site. He goes on to suggest that just because Schema.org markup is included it doesn't mean that the website in question is better/more relevent than any others.
Matt explains that the use of Schema.org markup for things such as recipes (a schema currently supported by Google) can provide a benefit in that the "recipes" search filter on the left side of the search results will draw on the schema defined information.
He certainly doesn't rule out that schema.org may impact on rankings in the future however I'm not holding my breath.
Aside from what is the obvious with schema.org inclusion - it allows content to be more easily interpreted and thus more likely to be included in the search results - personally I would have thought that the simple inclusion of schema.org would contribute to website quality signals for a ranking benefit. However even if this were to be true, the impact to be had would likely be negligible due to the simplicity of it in isolation as a ranking factor.
View the video and Matt's responses in full below, or take a look at the 900+ other videos produced by Google on their Webmaster Help YouTube channel here.