The New York City Police Department has issued guidelines for officers using social media as part of criminal investigations, according to the New York Daily News, which reported the news earlier this week. The guidelines come in the form of a five-page memo from Police Commissioner Ray Kelly which was circulated last week.

In social media, as in so many things, the conventional wisdom is "bigger is better"; Facebook is the best social network because it is the biggest, and smaller networks risk being dismissed as "also-rans." This consensus is based in part on the perception that scale is a prerequisite to effectively monetizing social networks, since revenue per user tends to be low (especially with business models relying on display advertising).

Four medical schools including the Albert Einstein College of Medicine at Yeshiva University, are offering training to aspiring doctors for the appropriate use of social media as part of the medical profession, thanks to a two-year grant from the Institute on Medicine as a Profession (IMAP) and the Josiah Macy Jr. Foundation.

Things are not looking up for publicly-traded social media companies, which will almost certainly discourage other firms (Twitter) from going public in the near future. In the most recent round of bad news, Zynga has lost yet another top executive, with the resignation of chief marketing officer Jeff Karp, while Pandora has suffered a brutal stock slide following news that Apple may launch a competing digital radio business, and Facebook's stock price remains in the doldrums.

Prepare for cognitive dissonance: members of the Taliban are posing as bikini babes on Facebook to spy on coalition troops in Afghanistan, according to the Australia Daily Telegraph, which cited pre-deployment briefings by the Australian military for soldiers headed to Afghanistan.

While no one would argue that attracting a billion users in less than a decade is anything less than epic, Facebook's glory days of exponential growth may be ending, as a slowing growth rate in the U.S. appears to be matched by a broader slowdown in global growth as well.

Private equity investors are bullish on social networks for doctors, judging by this week's announcement that Doximity, which allows physicians to connect and share expertise with each other in a secure setting, has raised $17 million in a second round of funding.

Social media has a bigger impact on the political views of Democratic voters than Republicans, according to a poll of 1,407 U.S. adults conducted by the Pew Research Center's Internet & American Life Project in January and February of this year -- although social media's impact on both groups is "modest," according to Pew project director Lee Rainie.

So Coca-Cola developed one -- an app -- to, you know, "make the world a happier place." Actually, the app is a new application on Coca-Cola's Facebook page, which may not yield happiness, per se, but it will at least enable the brand's fans to "declare their commitment" to spread happiness around the world.