Famke Janssen (Jean Grey) and Hugh Jackman (Wolverine) will return to their roles in X-Men 3, Variety said. Halle Berry (Storm), Patrick Stewart (Prof. X) and other actors are still in talks. Ian McKellan (Magneto) recently said he'd return for X3.
Screenwriter Simon Kinberg told Moviehole, regarding X3 being about Dark Phoenix: "I'm not allowed to say, but your guess is…. it was set up pretty well in the second movie. So, that's part of the third movie, but there's a new plot that's the story of the film."
And regarding James Marsden (Cyclops) not returning (because he's taken a part in Bryan Singer's Superman): "I believe he is now. The way I've written his character now – I'm trying to write him so he only has to come back for a couple of weeks. But he's definitely a part of the movie."
X-Men 3 will be directed by Layer Cake's Matthew Vaughn and debuts May 26, 2006.