This is really only good marketing. Avatar was a success even before launch (no one knew the story then). I remember watching Bones on television before the movie launch and there was a scene were people are painted and dressed like the Navi in front of the movie theater (before the actual movie launch!). So they were saying that it was a cult BEFORE being launched!
This is only VERY VERY GOOD propaganda. It is, sadly, a syntom of the times and how society are really made of IDIOTS that can be so easily manipulated to think that an unreleased movie is already a cult.
In fact, the story is nothing new (exactly what Americans did to Indians on the West or Spanish did to Maias and Incas on Latin America), but just with the SCI FI background added (gentle & inteligent aliens, some beautiful alien women, a crappy and unfounded love story, the bad guy that turns unexplicably good, a bit of ecology).
Nothing really new or interesting.
It is a sign of the times how people can even believe that that are lots of desperate souls crippled by this wonderful story that wanted to die and appear on Pandora. It is scary the level of manipulation we had these days. And how people are eager to fall for that (perhaps because we were made believe that that is so little we can do to change the reality we live in...)