Katy Perry guest stars with THE SIMPSONS. Just one of the special episodes airing this month on the animated series. THE SIMPSONS ™ and © 2010 TTCFFC ALL RIGHTS RESERVED. CR: Nicole Wilder/OX © 2010 FOX BROADCASTING CR: Nicole Wilder/FOX

Congrats to The Simpsons. The animated series has been given another full season, which will begin next fall.

Is the cast and production crew celebrating? Not quite yet says The Simpsons Executive Producer, Al Jean.

“More work,” he laughs when asked about his first reaction to the news they’d been renewed. “I called my wife and we’re both pretty happy, but there is a reason it has been on this long because we never sort of stop and congratulate ourselves. We just keep trying to think of how we can make it better.”

How do they keep the series fresh after so many years on the air? Jean tells us that the entire team keeps an eye out for similar storylines and avoids them at all costs.

“As show runner, one of my jobs is to go, ‘No, can’t do that. We already did it.’ And you really reject a lot of stuff before you get to something new,” Jean explains. “I think what we’re always looking for is that it’s, A: funny and B: connects with a real emotion of the family and if you get that, and even better if you can do something satirical with it, and you’ve got great actors, great writers, the animation guys work unbelievably hard, once you have that spark then you can really turn it into a flame.”

Jean admits that it takes dedication and an appreciation of their core audience that keeps their creative juices flowing.

“First, it’s a family so there are many permutations and many ways you can look at what’s happening to a family today and compare to 20 years ago and get stories from that,” he points out. “And then you really just grind it out, you never give up, you say that this is a show that people love and you don’t want to let them down.”

That’s been the case all through the 22 seasons of the animated series and Jean plans to keep the energy high over the next few weeks with some impressive guest stars.

“The next four weeks alone, we have guest appearances by Martha Stewart, by Jon Hamm (Mad Men) and [singer] Katy Perry, who is in a live action episode with Simpson puppets (shades of Muppets controversy), which we’ve done for the first time,” Jean divulges. “Martha Stewart’s segment is really funny. It’s a Christmas episode and Martha shows Marge how to do Christmas the Martha Stewart way.”

What does that mean for us viewers?

“She tapes Bart’s mouth shut and tapes ping-pong paddles on his back to make him look like a toy soldier and Marge says, ‘That’s going a little too far,’ Jean laughs. “Martha Stewart was really funny.”

They poke fun at Stewart, but they don’t roast her alive. Though Jean says Stewart was a good sport for almost everything…except where animals were concerned.

“She didn’t want to do harm to an animal, which is fine,” Jean recalls. “People who play themselves will often say I’m not going to do this or that and that’s fine.”

Jon Hamm from Mad Men will put Homer (Dan Castellaneta) through the paces.

“Homer goes undercover with Fat Tony’s gang and Jon Hamm is his contact to the real world,” Jean says. He was hysterical.”

And it’ll be all about The Simpsons throughout the month of November. Jean confirms that The Simpson movie is airing on Thanksgiving with all sorts of added footage. He’s not sure, however, how the network will handle Bart’s big nude scene in the film.

“I’m very curious to see how they’ll handle that,” he acknowledges. “We can’t show it on the show, so we’ll see what happens.”

After all these years, Jean still laughs as he’s describing scenes from The Simpsons - and that’s a good thing for viewers.

“Well, believe me, it’s a great job,” Jean acknowledges. “And part of that is how many times you laugh, no question. It’s insane. When (Producer) Morgan Spulock was going to do the documentary (on The Simpsons), he said he was going to watch every episode in a row and he said you physically can’t do it. And I never dreamed I’d be on a show that had that happen.”

The Simpsons airs Sundays, 8:00 p.m. ET/PT on FOX.