[Each week, our friend Ken Doctor — author of Newsonomics and longtime watcher of the business side of digital news — writes about the economics of the news business for the Lab.]

This week’s buzz is all about Google Buzz, the search giant’s entry into the status-update world. But the humming of social media — and its implications for news media — just keeps getting louder and louder. News people are in the social web, use the social web and write about the social web — but can they can make the social web part of their digital publishing businesses? That’s a big, important question, and one just dawning on many people in the news business.

First, let’s consider a number of datapoints:

— Nielsen reports that Internet users worldwide now spend 5.35 hours a month on social networks, up from just three hours a year ago. The social web is the new home page; remember how news sites all put up “make us your home page” buttons just a decade ago. News sites, of course, are lucky to break into double digits — 10 minutes — per month in usage.

— Facebook Mobile just announced yesterday that it busted through the 100 million user mark, up from 65 million in September.

— Bit.ly, one of the top “URL shortening service providers” — sends about two billion link referrals a month, largely given its Twitter stronghold. Question, of course, is how many of those may link to news or information; try, maybe, 20 percent, according to a recent Rutgers survey of social use that shows that 20 percent of posts in the statusphere come from “informers,” those that share news and information. The other 80 percent: the what-I-ate-today people.

— A recent study I did with Outsell said that 44 percent of news readers say they use social networks to share news and information. Of those, half use Facebook to do it; one in five use Twitter.

Clearly, there’s something big going on here. In my book, I characterized it as Law #1: “In the Age of Darwinian Content, You Are Your Own Editor. The old gatekeepers are disappearing. We’ve become our own and one another’s editors.” That old newsprint-based serendipity we bemoaned was being lost in the move to web searching and browsing is being reborn. Except now, as an unintended consequence of social publishing, we rely on story touts we’re seeing in Twitter, on Facebook walls, and in our email inboxes — that last function now augmented for Gmail users by Google Buzz. Among this vast infinity of story reading choice, we’re using our friends and colleagues as filters, though the process is still ungainly.

So if you are a news publisher, new or old, how do you engage this new world? I’ve checked around and there are precious few metrics to yet point to; it’s all so new. Consider, though, that “social media optimization,” a term that has buzzed quietly about Silicon Valley for a couple of years, will soon get real, becoming as much a fixture of our digital strategies as search engine optimization has become.

Within that social media optimization, we’ll see focused attempts to understand the value of social links, and, of course, the nuances among social links. Are Facebook users of a certain kind more likely to convert to become regular users of NYTimes.com (or Dallasnews.com or VoiceofSanDiego.org) than Twitter users? Which are more likely to convert to paid readers, for those testing metered approaches? How much do brand, topic and writer affect sharing? Social media optimization will meet propensity modeling — the Financial Times‘ secret sauce, now being tasted gingerly by the New York Times — all in an effort to find out how, where, when and why you can engage sustainable customers.

Of course, social media optimization strategies will encompass more than that, including restyled strategies to make URLs best readable by social media, to make sharing as eezy-peezy as possible (remember the “sharing wheel” in the Sports Illustrated tablet demo?) and to get writers and bloggers as enmeshed in the “social graph” as possible, without violating craft standards. In the end, though, it’s about how to grab more useful traffic, how to become as Pierre Omidyar recently said of his new Hawaii-based Peer News, “Our goal is to create the new civic square.”