The Collaborative International Dictionary of English v.0.48:

agitprop \agitprop\ n.
   1. [agitation + propaganda.]

   1. agitation and propaganda; -- used especially for such
      activities carried out on behalf of communist activists.
      [PJC]

   2. a person who disseminates messages calculated to assist
      some cause or some government; one disseminating
      agitprop[1]. Also called agitpropist.

   Syn: propagandist
        [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

agitprop
    n 1: political propaganda (especially communist propaganda)
         communicated via art and literature and cinema

Moby Thesaurus II by Grady Ward, 1.0:

25 Moby Thesaurus words for "agitprop":
   agent provocateur, agitator, catalyst, demagogue, exciter,
   firebrand, fomenter, incendiary, inciter, indoctrination, inflamer,
   instigator, mischief-maker, propaganda, propagandism, propagandist,
   provocateur, provoker, rabble-rouser, ringleader, rouser,
   seditionary, seditionist, troublemaker, urger