According to Variety, 20th Century Fox is currently running out of time on their production of their Daredevil reboot, which expires on October 13th, 2012. So in order to keep the production going, Fox is discussing lending the rights of The World-Eater, Galactus, along with his herald, the Silver Surfer. In return, Marvel would let Fox continue to work on their new Daredevil movie.
I’d like to point out that the article Marvel would “the rights to use characters from the “Fantastic Four” universe.” This could mean more than just Galactus and the Silver Surfer. This could even mean Dr.Doom, the Skrulls, or even the Fantastic Four showing up in later Marvel Cinematic Universe movies (despite there being a FF reboot in the makes).
Rumor has it that Galactus will play a key part in the future of the Marvel Cinematic Universe.