Books on porn are fast becoming like celebrity sex tapes…as ubiquitous as God and Ron Jeremy

New York- Once, they were exiled to the sleazy tenderloin districts of our cities.

Today, porn actors have become the darlings of the lit set and the toast of SoHo.

Gore Vidal and Salman Rushdie are among the intellectuals who’ve written essays ruminating on hard-core erotica in “XXX: 30 Porn Star Portraits,” by celeb photographer Timothy Greenfield-Sanders.

“Doubtless, sex tales were told [around] the Neanderthal campfire and perhaps instructive positions drawn on cave walls,” Vidal writes in the introduction to the book, which prestigious Bullfinch Press will publish on Oct. 1.

“Meanwhile, the human race was busy establishing such exciting institutions as slavery and its first cousin, marriage.”

Rushdie writes that in conservative societies, porn “sometimes becomes a kind of standard-bearer for freedom, even for civilization.”

Feminist Faye Wattleton inveighs against porn-phobic “religious dogma that does not comport with human need.”

“Alien” author Whitley Strieber writes about sex with extraterrestrials. Also contributing are novelist Francine du Plessix Gray (on the Marquis de Sade, “The Big Daddy of Porn”), actor John Malkovich (who remembers seeing his first porn movie, “Emmanuelle,” in college) and director John Waters (reflecting on sex addiction).

But the main attractions – the money shots – of Greenfield-Sanders’ book are his portraits of adult performers, like Jenna Jameson, dressed and undressed.

The photographer, whose previous subjects have included Sens. Hillary Clinton and John Kerry, several Supreme Court justices and both Presidents Bush, says: “There’s a great openness about these [porn] people that’s good.”

The book is part of the lensman’s multimedia juggernaut, which will also include a major show at the Mary Boone Gallery (opening Oct. 30); an HBO documentary, “Thinking XXX”; and a soundtrack CD featuring music by his friend Lou Reed.

“I’m even thinking about doing a perfume,” says Greenfield-Sanders, “but I can’t decide about what it would smell like.”

We asked him if his year-long immersion into the skin trade improved his sex life with his wife, Karin. “I refuse to answer the question,” says the artist.