A liberal advocacy group looking to break through the torrent of ads about health care reform took a chance on Facebook that it says paid off big, a possible sign of things to come.

Americans United for Change decided to go after a specific audience -- Sarah Palin supporters -- by using keyword targeting long offered by Facebook. The feature takes advantage of profile information and group and page memberships to deliver a message to a select audience. So targeting the keyword "Sarah Palin" let Americans United for Change advertise to anyone sounding off about the former Alaska governor's "death panels" theory, including her more than 850,000 self-proclaimed fans.

It was the first time the group had tried such specific targeting, and spokesman Jeremy Funk calls it "a very successful experiment." Over the course of the weeklong campaign, the ad got about 220,000 impressions, and as a result of some media exposure and about 530 clickthroughs (a higher rate than most Facebook ads, Funk noted), the group managed to get 4,600 people to write Palin protesting her statements on health care.

A few years ago, such a pinpointed campaign would have been difficult to pull off, but as more and more people join social networking sites and publicly share opinions on nearly everything (even while those sites take advantage by equipping advertisers with microtargeting tools), yesterday's advertising dreams have become today's reality. And if Americans United for Change's claims of success are any indication, keyword targeting with Facebook could have a significant impact on how advocacy groups make their cases.

"There's really no other advertising network that so specifically hits the people you want to hit," said Kombiz Lavasany, a new media consultant at New Partners who worked on the Americans United for Change campaign. "It's got a lot of potential for issue-based targeting."

The concept is similar to buying ads against keyword searches on Google, except Facebook targeting allows groups to reach individuals who are already talking about and engaged with a subject, rather than just Googling to learn more.

Keyword targeting has been available since Facebook advertising launched in November 2007, and it is widely used among advertisers, a company spokesperson said, though it won't release information on how often it is used. One of the factors that could drive more advocacy groups to use the targeted messaging is the site's changing demographics. In the first six months of 2009, Facebook users in the 55 and over category increased by more than 500 percent, analysis by iStrategyLabs found.

As older Americans -- who tend to vote at higher rates and be more politically aware -- flock to the site, they provide a readymade audience for advocacy groups, Lavasany said. He's already working on Facebook campaigns for other interest groups.

But keyword targeting isn't without its potential drawbacks, warned Mark Drapeau, a social media consultant and adjunct professor of media and politics at George Washington University. Imagine groups going back and forth with ads targeting each other's supporters, he said. That kind of campaigning could drive people to tune out or stop using Facebook to express political stands.

But the bigger problem on the virtual platform could be the creation of misleading ads or fake Facebook accounts, Drapeau said. The Federal Trade Commission regulates ads on television and radio, but on social media networks, issue-based campaigns, especially for controversial issues, could get out of hand quickly, he predicted.

Advertising on social media sites is "unregulated and yet very sophisticated," Drapeau said. "To a large degree there are no rules about what you can do or can't do on these sites."