We have some encouraging Alien prequel new thanks to a German interview with Carmen Scheifele, the wife of H.R. Giger. For those that are unaware, he created the original Alien creature designs, along with other art for the original film. Apparently, he will be working on this film and Carmen mentions that there will be two prequels and both will be shot in 3D.
I don't doubt the 3D bit, because everyone is going in that direction, but the two prequels idea is simply a rumor that has been shot down by Fox already. Studios have previously denied rumors that turned out to be correct, but until we have official confirmation, let's just consider H.R. Giger's involvement a rumor from a VERY credible source.