The story is based on Chris Claremont and John Byrne's comic book arc in issues #141 and #142 of Ultimate X-Men from 1982. The time travel aspect Hugh Jackman mentioned stems from an alternate future where an important Senator is killed by the Brotherhood of Evil Mutants, which leads to all mutants being hunted down by Sentinels.
Bryan Singer is directing from a screenplay by Simon Kinberg. Production is scheduled to begin in Montreal very soon.
X-Men: Days of Future Past was released May 23rd, 2014 and stars Hugh Jackman, James McAvoy, Michael Fassbender, Jennifer Lawrence, Halle Berry, Nicholas Hoult, Anna Paquin, Ellen Page. The film is directed by Bryan Singer.