Animal Farm

Almost instantly after the novel's publication, it became the subject of revisionism. In one instance, the CIA made an animated film version of the book in which they eliminated the final scene and replaced it with a new revolution in which the animals overthrow the pigs (see the 1999 Hallmark film version for another change in ending). They distributed the film as anti-communist propaganda, which is ironic when one considers the novel's own censure of the propagandist rewriting of history.
More info : http://www.netcharles.com/orwell/articles/col-nyrblist.htm
http://educationforum.ipbhost.com/index.php?showtopic=13699
http://www.spartacus.schoolnet.co.uk/JFKmockingbird.htm