Google wants Internet users to "experience the full richness of the web." Part of this experience is browsing the web on mobile devices. How about including whether a site uses a responsive design as part of a website's Pagerank, Google? Check.
It will no longer be sufficient to have a conventionally designed mobile version of your site, it must use a responsive design. But that's only the short of it. Implementation counts two. For example, redirecting users from a desktop page to an irrelevant (or non-corresponding) page on the smartphone-optimized version will also lead to downgrading your website pagerank. Ouch.
Read all about it here - Google's blog posts tagged mobile.
With millions of websites incorporating a responive design in the coming months, yours should count among them. As we often repeat to our clients, "Do it once, do it right."