Can 800,000 Palin Facebook fans be wrong? Liberal group calls her a liar

When Sarah Palin posted her notorious Facebook message warning the public of so-called "death panels" included in President Obama's health-care reform package, many liberals were not amused.

In response, the liberal group Americans United For Change took the fight right back to Palin -- and more importantly, to the 827,000 Facebook supporters of the former Alaska governor and vice-presidential nominee.

The group purchased an ad viewable "to anyone interested in 'Sarah Palin,'" according to Facebook, which includes Palin's picture and the following words underneath: "Health insurance reform is too important for outright lies; tell her to stop lying about death panels."

The liberal group's use of Facebook's highly targeted advertising platform underscores the increasing sophistication of online advertising systems, which let businesses, politicians, and interest groups direct their messages to hyper-specific audiences that share certain interests or characteristics.