PostRank, a social analytics firm, has announced that it has been acquired by Google. Marketers should take this as a sign that Google is getting serious about the social aspects of search, and this is further evidence that +1 data might soon serve as a ranking signal.

The analytics firm has traditionally monitored where and when branded content generates engagement on the web. Now, PostRank says it will be “working with Google's team to build more useful tools for measuring engagement online.”

For its part, Google has remained mum about the acquisition. Google insiders, however, have not been quiet about their hopes for building a more social search experience. Former Google CEO Eric Schmidt recently spoke about Google's social shortcomings, saying if the company had more social data it could “compute a better answer, because we’ll know more about you,” Digital Trends reports.

Plus, Brafton has reported that with the launch of the new +1 button for websites, many marketers might want to implement the plguin with SEO in mind. Google's Matt Cutts has openly said that Google +1 data is “definitely a signal we're paying a lot of attention to … It has tons of potential.” If, of course, users start “+1-ing” content…