Sigourney Weaver basically confirms that anyone who watched Avatar for the storytelling and cried over her character's death wasted their tears. "I'm not at liberty to tell anything. [James Cameron] just said, 'You know, in science fiction, death is not really death,'" she told shocktillyoudrop.com when they asked about the sequel.
She also says that, as of now, she's not going to play a role in the new Alien prequel. But she's always willing to give advice, if Natalie Portman wants to give her a call. "If they needed help with the story, I could probably help them because I probably have a good sense of what people appreciate in the series and what they don't care about," she said.
Interview: Sigourney Weaver on the Alien Anthology [shocktillyoudrop.com]