From WebProNews: "...“We’ve been wanting to work on this for a long time, but our data scientist was previously tied up on other items (and we’ve just hired a research assistant for the project),” Fishkin tells us.
“The original catalyst was the vast quantity of emails and questions we get about whether a page/site is ‘safe’ to acquire links from, or whether certain offers (you know the kind – ‘$100 for 50 permanent text links guaranteed to boost your Google rankings!’) were worthwhile.”
“Tragically, there’s a lot of money flowing from people who can barely afford it, but don’t know better to spammers who know that what they’re building could hurt their customers, and Google refuses to take action to show which spam they know about,” he continues. “Our eventual goal is to build a metric marketers and site owners can use to get a rough sense of a site’s potential spamminess in comparison to others.”
“A score (or scores) of some kind would (eventually, assuming the project goes well) be included in Mozscape/OSE showing the spamminess of inlinks/outlinks,” he explained in the Google+ announcement."
Rand Fishkin announcement: https://plus.google.com/u/1/111294201325870406922/posts/gbeKneoTDh8