Advertisers won't be the only ones watching your Facebook activity with interest. Now, the New York Police Department will be checking it out, too.

The NYPD on Wednesday announced it formed a new unit to track people who discuss their crimes on Facebook, Twitter and MySpace. The unit will "mine social media, looking for info about troublesome house parties, gang showdowns and other potential mayhem," according to the New York Daily News.

Other law enforcement agencies have used Facebook and Twitter to keep people informed of criminal activity. Such programs include digital "wanted" posters, police blotter blogs and the use of online tipsters. The Boston Police Department has used Twitter to monitor chatter around the city since 2009, and the FBI employed Facebook, YouTube and Twitter outreach to apprehend longtime fugitive James "Whitey" Bulger in June.

Image courtesy of Flickr, Vincent Desjardin