The Simpsons had its annual screening at Comi-Con this past week, with a few fresh details regarding Season 20 coming to light:
 
EW.com reports the following:
 
* September 28th's season premier is another "Homer Gets a New Job" episode - this time, he's a bounty hunter, tracking down Snake and his pregnant girlfriend Gloria.  That means Julia Louis-Dreyfus will return for the third time to voice her now-familiar character.  Joe Mantegna is also set to appear in this episode, reprising his Fat Tony role, and Robert Forster will also guest.
 
* The October 5th episode will feature Bart discovering Denis Leary's cell phone and using it to stir up a ton of trouble.  The show will also guest-star Brian Grazer, who's an unwitting victim of Bart's when everyone's favorite prank caller impersonates Leary and accepts Grazer's offer to star in the big screen adaption of "Everybody Poops".   
 
* "Lost Verizon" will officially feature Matt Damon.
 
* This year's Treehouse of Horror Episode will include a Milhouse-centric parody of "It's The Great Pumpkin, Charlie Brown."  It will also include an election-themed segment involving Homer and an ornery electronic voting booth. 
 
* A December episode will feature Mr. Burns winning a basketball team in a poker game, and will feature Dallas Mavericks team owner Mark Cuban and Amazon.com CEO Jeff Bezos.
 
* Full details are out on the Seth Rogan-penned episode - it will feature Comic Book Guy creating a superhero; he ends up with a movie deal, and Homer lands the part of the hero.  Rogan is set to play Homer's trainer as he tries to get into shape for the role.  It's not scheduled to air 'til next year.
 
* Additionally, the episode "Lisa The Drama Queen" has been added to the list of official episode titles.

Source:
EW.com: 1 and 2