Looks like Sigourney Weaver is making the press rounds lately; she's been talking up her role in James Cameron's Avatar, while preemptively turning down parts in any future Alien or Ghostbuster films. As you're probably already aware, Weaver is reuniting with Cameron for the first time since Aliens on Avatar, where she'll be playing a botanist and mentor to the lead character, a former marine (as played by Sam Worthington).
In one interview for EW, Weaver calls the Avatar script a "dizzying ride," and notes that her "jaw was permanently dropped the entire reading." Of course, the majority of all questions usually end up mentioning Aliens, her relationship with Cameron and whether or not she'd be interested in reprising the role of Ripley for any future Alien-related sequels. Regarding the latter, fortunately Weaver took the words right out of most of our mouths; she tells The Desert Sun, "I love the character, but I think the monster, once they did the other film (Alien vs. Predator), which I never saw, but that really maxes our monster out."
But what about Ghostbusters? Apparently, Dan Aykroyd is keen on doing some sort of CGI-based third installment (which immediately has me imagining something that belongs alongside the rest of the Saturday morning cartoons; in fact, wasn't there a Ghostbusters cartoon back in the day?). Well, according to Weaver, that's not going to happen either; at least, not with her: "I think all of us are busy doing so many things and it's wonderful all the films are so well loved and they certainly were fun to do. But I think if you do it right the first time, sometime it's better to move on to something else." And we shall move on ... Avatar is set to arrive in theaters in 2009.