And to add even more confusion over whether Prometheus is Alien related or not, Dark Horizons have just posted this:
“Another source shot me a message today having read an early draft of the script saying that a “bioweapons planet” is the only link to the “Alien” films in it and it’s a tenuous one at best.”
Key thing to note there is that the source talks of an early draft. The shooting draft may have been changed if SkyMovie’s contact is correct. Thanks to Darkoo for the news.