It appears that Hugh Jackman has officially started production on Bryan Singer's X-Men: Days of Future Past. The director tweeted the below image of the actor's back along with the word "fitting," likely referencing a costume fitting. As you can see, the actor is clad in a brown leather jacket, potentially aimed to represent the one the character wears on the iconic cover to X-Men #141 (pictured to the left).
Reprising his role as Wolverine for the seventh time, Jackman joins Ian McKellen, Patrick Stewart, James McAvoy, Jennifer Lawrence, Michael Fassbender, Nicholas Hoult, Anna Paquin, Ellen Page, Shawn Ashmore, Peter Dinklage, Omar Sy, Halle Berry, Daniel Cudmore, Fan Bingbing and Boo Boo Stewart in the mutant ensemble, set for release July 18, 2014.
The film is based on the comic book storyline "Days of Future Past," which ran in Uncanny X-Men #141 and 142 back in 1981 during Chris Claremont and John Byrne's run and introduced the idea of an alternate future for Marvel's mutants that grew out of the Brotherhood of Evil Mutants killing an important senator, leading to a future where all mutants are hunted by Sentinels.