The Simpsons was confirmed on October 7, 2011 as being renewed through its 25th. This occurred as part of the negotiations with the show's main actors over their salaries as a means of keeping the show going. Season 25 premiered on September 29th, 2013 and will end in May 18th, 2014.
Al Jean, executive producer of The Simpsons, has said he views the two additional seasons as a beginning and that it is a goal to complete thirty seasons by the end of the decade. Season 25 aired on September 29th, 2013 with "Homerland" as the first episode of the season. 
Aaron Sorkin will play himself in "Four Regrettings and a Funeral," where he will help Kent Brockman to decide whether or not to work for FOX news. Joe Namath and Gordon Ramsay will also make cameos. 
Stan Lee will make his second appearance on The Simpsons in this season. 
Kristen Wiig will make her second appearance on The Simpsons in an episode called "Homerland," playing a character hired by Lisa to investigate Homer after he acts oddly polite after a Nuclear Power Convention. This episode will be the season 25 premiere. 
Anderson Cooper will be on an episode of The Simpsons where Lisa befriends a girl (guess voiced by Eva Longoria) who is her match in every way, expect one, she's a conservative Republican. "They run up against each other in the second-grade election," says showrunner Al Jean, "and then we flash to the future where they're [engaged] in an actual presidential debate - and Anderson is the moderator." 
Will Arnett from Arrested Development and 30 Rock fame will voice Detective Gratman, a FBI anti-piracy boss who has the task of hunting down Homer Simpson after he illegally pirates a movie in "Steal This Episode." 
Daniel Radcliffe has a second Simpsons appearance as an older boy named Diggs who has an interest in falconry. 
Billy West, Katey Segal, John DiMaggio, Phil LaMarr and Maurice LaMarche will reprise their Futurama roles for a Futurama/The Simpsons crossover episode, where Bender tries to kill Bart because Bart messes up the future. 
Judd Apatow, writer/director of Knocked Up, Superbad and The 40-Year-Old Virgin, will be writing an episode of The Simpsons in season 25 where Homer is hypnotized to think he's ten years old and becomes friends with Bart.  He is also expected to guest star. 
Don Payne, who passed away on March 26th 2013, will have two episodes that will air posthumously in the 25th season, "White Christmas Blues" and "Labor Pains". 
Kevin Curran is writing an episode called The Winter of His Content, set to air in Spring 2014. Music editor Chris Ledesma attended the table read, and said on his Twitter that Hank Azaria "acted his ass off." 
"Bart's sister (His Baby Sister)" will be the first ever episode about Bart and Maggie's relationship.
There will be a sequel to Holidays of Future Passed.
There will a "very musical" episode.
The Simpsons has been officially renewed for a twenty-sixth season. 
One episode this year will feature Homer as a referee at the World Cup Finals.