Greenberg star Greta Gerwig has boarded Ivan Reitman’s upcoming untitled relationship comedy. The project, which was originally called Friends With Benefits, stars Ashton Kutcher and Natalie Portman. The Elizabeth Meriwether-written movie centres on a casual couple dealing with the differences between forming a sexual relationship and a lasting emotional bond. Gerwig will play Portman’s best friend in the picture. The movie is due in US cinemas on January 7, 2011.

Source: Digital Spy