With last year's successful feature film, the recent launch of season 20 and last month's Emmy win for Outstanding Animated Program, Fox's "The Simpsons" doesn't seem to show any signs of slowing down. Executive Producer Al Jean talked to our Jim Halterman about the show's upcoming celebrity guest voices and storylines as well as the odds of another feature film.

Asked how long "The Simpsons" can possibly run, Jean shared where they are at in this stage in the game. "I'll tell you," Jean said, "we signed the cast for four years, including this one, just recently and the Emmy was wonderful ad I really feel, creatively, we're still doing terrific work and I don't see an end for awhile. The movie and the [amusement park] ride were both huge successes so I think people still really want 'The Simpsons' in their lives."

Since "The Simpsons" debuted in its half-hour format in 1989, Jean believes things have definitely come a long way. "The biggest technological change has been the influence of computers. When we started, it was hand-drawn animation in films only and now [in terms of] hand-drawn animation, we were one of the last movies ever." Jean also talked about some of the animation predecessors and the differences between them and "The Simpsons." "Even though there were shows in primetime in the past like 'The Flintstones,' I don't really think they were aimed at adults, I think they were aimed mostly at children. I'm not saying we tried to have risque content, per se, although that is partly the cast, but we have aimed our show at the adult audience and done things that we think are smarter. The kids won't necessarily get it, but they'll watch because of the forum."

Celebrity voices have long been a staple of "The Simpsons" and the new season offers up such guests as Jodie Foster, Anne Hathaway and Seth Rogan. Jean gave a preview of how they incorporated these celebs into his animated world. "We do a parody of 'The Fountainhead', the Ayn Rand book, where Maggie Simpson is in a preschool where she's trying to build these beautiful block buildings and the preschool teacher keeps knocking them down because it's too creative. At the end, she goes on trial, like the end of 'The Fountainhead' and Jodie Foster does Maggie's voice."

Hathaway is featured when "Bart meets a girl who is really sweet and thinks he's really a nice kid and not a brat, so he tries to hide his true identity from her and then she finds out what he's really like and they break up," Jean explained. "[Hathaway] was very funny; she's really hilarious to work with."

Rogan, who co-wrote an upcoming episode with Evan Goldberg, also lends his voice in the same episode. Jean recounted, "Comic Book Guy creates a superhero called Everyman and his power is that any comic book that he touches he gets the powers of the hero of that comic. They make a movie starring Homer and Homer is overweight and doesn't look like a superhero so Seth Rogan plays a personal trainer who is going to get him in shape."

Besides celebrities who voice many of the guest characters, there is one coveted group that Jean said the series has been unable to secure no matter how often they ask. "U.S. Presidents. We've tried to get them going back to � I think Richard Nixon was actually the first when he was still alive. They've all said no. Ronald Reagan, or his assistant, wrote us a very polite no, but that was the closest we got."

Jean also explained that because each episode of "The Simpsons" takes about a year to produce "we can't do jokes like 'The Tonight Show' or 'The Daily Show.'" He does see advantages to this restraint, however, in that "if you watch the show from four years ago, it still holds up. We don't take inconsistent positions that you might do if you have to give an opinion every day on what you think."

A little political humor did happen to make it into the annual "Treehouse of Horror" episode, which airs on November 2nd. "The opening is a little thing about the election where Homer tries to vote for Obama but the machine keeps changing it to McCain and then finally kills him." In addition, Jean revealed other stories in the much-anticipated episode. "We do a satire of the fact that they can take dead celebrities, put them in commercials and do whatever they want. So Homer starts killing living celebrities so they can use them in commercials. " Also, a particular animated Halloween TV classic is parodied this year when "The Grand Pumpkin, totally different legally, comes to life and he's so mad at the way humans treat pumpkins that he tries to kill them all."

With the series' popularity having proved itself on the big screen, the inevitable question is when to expect another "Simpsons" feature film. "We definitely would love to do it if we had a script we believed in as much as the first one but that script took four years to do and that was after it took awhile to make a deal with the cast." Jean hinted that the wait could be longer than some fans would like. "My preference would be, because it was so much work to do both the show and the movie simultaneously, to wait until whatever that day is when the show is done, and to do another movie." To emphasize priorities, he added, "To me, nothing is more important than making the show as good as it can be."

One common practice with a successful series that Jean has always been against is the spin-off series. He did reveal that the subject has been brought up in the past. "The decision was that it would be very difficult to do at the same time as the show and that we preferred to put our energy into doing the movie and the ride." Jean also said, in terms of breaking off characters and stories into another franchise, "I like the show having such a wide universe and not splitting it. I never liked it when they took Fish and moved him off 'Barney Miller' and those things always seemed like they were the loopholes. I just like doing new media where we can go in and kind of make fun of it and do 'The Simpsons' take on it, as opposed to splitting what we have."

With this being the 20th season of "The Simpsons," the series is now coming closer to being deemed the television series with the most episodes produced. And, though some might thing that Jean and his fellow writers/producers wouldn't worry about things of that nature, Jean admitted, "we actually do count episodes. I think we're about twelve ahead of ['Law & Order']. They started a little later and they do slightly fewer per year. In number of episodes, we're ahead of them but we're still behind 'Lassie' and 'Gunsmoke' and 'Gunsmoke' did 600. They used to do 40 a year so that's a rough one. We are up to 445 in terms of records."

Finally, Jean shared that even after all these years, he's content staying where he's been since 1989. "What keeps me interested is when you see something that is a good idea, you're able to take the writing staff and translate it into something that is funny and a pleasure to watch. It's the greatest way to vent what you feel about life. It's just a wonderful place to be and I'm really happy to be there."

"The Simpsons" can be seen every Sunday night on FOX at 8:00/7:00c.