Forget 20, Forget 30. 40 Is Hot!

The conventional wisdom in media and fashion has always been that at 40, an actress or model has reached her expiration date and can kiss her career goodbye.

But the original supermodels of the '80s and '90s -- Linda Evangelista, Christy Turlington and Claudia Schiffer -- and 40-something actresses like Brooke Shields, Mary-Louise Parker and Debra Messing are challenging that notion by continuing to work on major advertising campaigns and hit television shows.

"Women in their 40s are here and they're not going anywhere," said Albert Lee, a senior editor at US Weekly. "In politics, media and fashion, everyone is finally waking up to this sleeping giant demographic. These are the women at the hub of our culture."

Among the celebrities who have joined Club 40 are Halle Berry, Courtney Cox, Vanessa Williams, Nicole Kidman and Janet Jackson. And with some notable exceptions, a lot of these women seem to be aging gracefully, without overdoing the Botox.

"Women aren't as afraid to grow older," Lee said. "It's about retaining their femininity and owning it in a way that's not desperate, like, 'I'm a 42-year-old woman who wants to look like 18. I can still go get my hair blown out and buy some nice makeup and go to yoga and Pilates classes. Before it was either give up and put on some high-waisted mom jeans and drive a minivan or try to stay forever young wearing dresses with a hem too high and a bust too low and become the mom everybody whispers about. Now there's a middle path."

Lee believes women in their 40s have finally captured the imagination of advertisers and media executives, who are taking notice of this largely untapped market.

"Advertisers have excluded older women for so many years, now they are saying that was actually a dumb financial move," said Jennifer Pozner, executive director of Women In Media & News, a media analysis, advocacy and education group based in New York. "Why don't we combine the culture's current nostalgia for anything '80s with models who still look gorgeous?"

Supermodels: Sexy at 40

The women who invented the supermodel phenomenon are back in the spotlight after leaving to have children and pursue other interests. They have eclipsed their teenage rivals to helm this season's most coveted collections. Evangelista, 43, is the face of Prada; Schiffer, 38, is fronting Chanel's main collection and Turlington, 39, is promoting the designer's eyewear. And they are not the only ones.

Naomi Campbell, 38, who has hardly ever stopped working, will be representing Yves Saint Laurent this season. More impressive is her predecessor Christie Brinkley, who, at 51, renewed her association with Cover Girl and is currently the face for its Advanced Radiance cosmetics for older women.

"A fashion house decided to listen to the customer rather than follow the trends," said Didier Fernandez, ad agent at New York-based DNA Models, which represents Evangelista. "You don't see a 20-year-old buying a $5,000 product. That might be why Prada and Chanel decided to go for a woman instead of kids."

On the screen, some actresses in their 40s are also proving that age is just a number. Parker, 44, is in her third season of Showtime's dramedy "Weeds" in which she plays a pot-dealing suburban mom. She won a Golden Globe in 2006. Brooke Shields, 43, is returning for the second season of NBC's "Lipstick Jungle" in which she stars as a movie executive.

Messing, who recently turned 40, will return in her role as the first wife for the second season of the USA Network series "The Starter Wife." She will also be part of the ensemble cast that includes Meg Ryan, Annette Bening, Eva Mendes and Jada Pinkett Smith in the upcoming film "The Women" by "Murphy Brown" creator Diane English.

Lee attributes the onscreen 40-something shift to the success of ABC's "Desperate Housewives" and the movie "Sex and the City." Four of the women in "Housewives" are over 40. "They are not playing the mom to the sexy kids or the over-the-hill mom," Lee said. "They are actually playing the lead characters. They showed a lot of people that women over 40 don't all have to be Florence Henderson."

Success of Sex and the City

"Sex and the City" was also a turning point. "It was a moment when people woke up and said, 'Oh, women go to the movies too,'" said Lee. "All the actresses are 40 or older. For the studios to realize that women want to see an exaggerated version of their own lives is huge."

But before someone declares it the year of the older woman, Pozner cautions that the driving force behind all these shows and movies and advertisements with women in their 40s is an advertising industry that is looking to make more money by selling products.

Nowhere is this clearer than in Messing's show "The Starter Wife," which has written Ponds products into the show, Pozner said. She points to one scene that has Messing examining her wrinkles in the mirror and debates whether a Ponds wrinkle cream would actually help her or not.

"I caution against seeing this as more than a trend or fad," said Pozner. "We are more age and more image obsessed than ever before."