A few weeks ago (late August, 2000), the GOP ran a commercial message endorsing George Dubya Bush and criticizing Al Gore. One of the things the advertisement did was flash 'bureaucrats' on the screen, two parts at a time. First 'bureau', then 'crats'. However, the 'c' was very much off screen, leaving only the tips of the 'c' and the word 'rats'. Many think that this is intentional, and the GOP has taken flak for running such an ad.
However, the GOP cannot be liable, the only ones who can be liable are the stations who ran the advertisement. A court needs to prove that the stations knew of the message before running the advertisement.
Since 1974, the FCC has spoken against subliminal advertising. This does not stop advertisers, however, as they know that the strongest message is the one which is not immediately apparent. It is best to keep a keen eye when viewing advertisements, lest be taken in by the contents without realizing it.