Jake Gyllenhaal Goes to Prison, Packs on Pounds!

Jake Gyllenhaal reveals why he wanted to pack on muscle for his role and spills on filming Prince of Persia

Visiting inmates, bulking up, getting cozy with Natalie Portman—it's all serious work for Jake Gyllenhaal while filming Brothers. He spills all about the buzzed-about drama, and dishes on next summer's action-packed Prince of Persia.

I also talked to his costars, so hit the jump to hear what Portman has to say about politics, and Tobey Maguire leaks about Spidey 4...