Most news sites, including Daily Dead, have been covering all Prometheus casting news, because everyone was expecting a small cast like the Nostromo crew in Alien. Prometheus, however, continues to reveal new cast members and James Payton (Robin Hood, Captain America) posted a Tweet (now removed) indicating that he's also in the film: "Back to the spaceship after my stay of execution yesterday. Pinewood, here I come. *yawn*"
He'll join the already-revealed cast members Noomi Rapace, Michael Fassbender, Charlize Theron, Idris Elba, Guy Pearce, Rafe Spall, Sean Harris, Logan Marshall-Green, Kate Dickie, Benedict Wong, and Emun Elliott.
There is also news (via Moviehole) that Fox and Scott Free (Ridley Scott's production company) are still interested in Alien sequels : "I don’t know much, but I’ve heard whispers that sequels (to the original quadrilogy – Ripley’s story) might be back on the cards; the whole ‘Alien Planet’ idea is still very much something everyone over at Fox and Scott Free are interested in. You ain’t see the last of Facehugger."