Well... it is a recognizable fact that people with agendae use every asset they have to spread their "gospel". In Moore's case, and the case of many others, this is film. In some cases, websites.. or books. These are all within our first amendment right which has always been, and will continue to be abused by both ends of the spectrum.
I think in the end people are capable of making their assessments about the way things really are. We're all capable of critical thinking.
I suppose the only thing that REALLY bothers me is the fact that so many figures, including the media, whose sole purpose is to provide objective information, dub this propoganda as "fact", "information", "documentaries", etc. Re-read the definition of a documentary above... and you'll see what I mean.
The local news stations in LA refer to Fahrenheit 911 as a documentary. Seriously now guys... regardless of your political agenda, you've gotta laugh at that one.