There was a photo of an advanced screening ticket for Prometheus posted online within the past week and people only seemed to notice one thing; the fact that it had an R-rating.
Personally, I don't care about R-ratings. I think the MPAA is giving movies that rating based on stupid things and that it doesn't really mean anything anymore. I can't count how many PG-13 movies I have seen that deserved an R. With that said, this really isn't a big deal. Most of Ridley Scott's movies have been R-rated. Parents and guardians will still take their underage children to see this because it looks awesome.