Zooey Deschanel joins the cast of the new Paul Rudd movie...

...and she's not alone, according to The Hollywood Reporter:

Elizabeth Banks, Zooey Deschanel, Emily Mortimer and Rashida Jones will star opposite Paul Rudd in "My Idiot Brother," a comedy being directed Jesse Peretz and produced by Anthony Bregman's Likely Story and Big Beach's Peter Saraf and Marc Turtletaub.

"Brother" centers on an idealist (Rudd) dealing with his over¬bearing mother who crashes at the homes of his three ambitious sisters and brings truth, happiness and a sunny disposition into their lives while also wreaking havoc.

Banks, Deschanel and Mortimer will play the sisters.

Banks is a career-driven single about to get her big break in journalism after spending years writing about accessories at a fashion magazine; Deschanel is a bisexual whose flakiness and lies are getting in the way of moving forward with her caring, responsible girlfriend (Jones); and Mortimer plays a Park Slope mom too worried about having the perfect life and children to notice that her marriage is falling apart.

Evgenia Peretz and David Schisgall wrote the screenplay for the pic, which is slated to go before cameras next month in New York.

Banks, repped by UTA and Untitled Entertainment, next appears opposite Russell Crowe in "The Next Three Days," directed by Paul Haggis. She also will appear in "The Details" opposite Tobey Maguire and Laura Linney.

Deschanel, repped by CAA and Seven Summits Pictures and Management, most recently starred in "(500) Days of Summer" and next appears this year in "Your Highness," starring James Franco and Natalie Portman.

Mortimer, repped by ICM, Brillstein Entertainment Partners and Independent Talent Group, most recently appeared in "Shutter Island."

Jones, repped by UTA and Brillstein Entertainment Partners, co-stars on NBC's "Parks and Recreation" and recently wrapped David Fincher's "The Social Network."

-It's certainly got a great cast...let's cross our fingers and hope the script is up to snuff.