Last week's Grammy Awards may have been given out for music, but backstage one of the most popular subjects of talk was the movies. At times it seemed as if every winner, presenter or passer-by was working on a script, writing music for a film or thinking about making the jump from vinyl to celluloid.

Jazz-pop keyboardist Herbie Hancock spoke of French director Bertrand Tavernier ("Coup de Torchon") and his upcoming "Around Midnight," which finds Hancock involved in the story of an American musician and his friendship with a Parisian jazz buff. Ten minutes later, heavy metal singer Dee Snider of Twisted Sister was talking about the script he's writing with Firesign Theater mainstay Peter Bergman. "Unlike the Prince movie 'Purple Rain,' " Snider grinned, "we're not gonna try to do all the acting ourselves."

Randy Newman, picking up an award for his score of "The Natural," said he's writing a script with Steve Martin and "Saturday Night Live" producer Lorne Michaels. Performance artist Laurie Anderson said she's working on a film. And Jermaine Jackson confirmed that he's been selected to play the late Marvin Gaye in a filmed biography.

Big winner Tina Turner had a head start on most of the others, though. She's already finished work on the third "Mad Max" film, and on her biggest night in the music business she admitted, "Movies have always been my dream." Apparently MTV just isn't enough for some people . . .

The first year in business as an "instant major" studio found Tri-Star Pictures achieving one important goal: It got lots of Oscar nominations and, presumably, industry respect for "Places in the Heart" and "The Natural." But Tri-Star had no blockbusters -- that's the studio's goal for 1985. Of its projected 1985 release slate of 18 films, high hopes are pinned on four in particular: "Berry Gordy's the Last Dragon," a musical fairy tale produced by Motown Records chief Gordy and featuring a batch of would-be hit singles; "Rambo: First Blood II," the further adventures of Sylvester Stallone as a rampaging Vietnam vet; "Volunteers," a comedy directed by Nicholas Meyer ("Star Trek II") and starring Tom Hanks and John Candy as new Peace Corps volunteers; and "Santa Claus, the Movie," a Christmas entry from the "Superman" production team.

If these releases start to make significant money, however, listen for loud grumbling from the direction of Columbia Pictures. Not from that studio's chiefs, who share in Tri-Star's profits with CBS and HBO, but from lower-level employes who've grown to resent a thrifty arrangement that has Columbia staffers handling distribution chores for the busy new studio, effectively doubling their workload without extra compensation . . .

Casting notes: Martin Sheen, whose son Emilio Estevez has been getting most of the attention in the family lately, is set to star in "Chain Reaction," an independent feature that begins filming in Paris this month . . . Hunter Carson, who made quite a splash in his film debut as Harry Dean Stanton and Nastassja Kinski's son in "Paris, Texas," will costar with his mother Karen Black in Tobe Hooper's upcoming remake of the '50s science fiction story "Invaders From Mars." Carson's used to keeping it in the family -- Sam Shepard's cowriter on "Paris, Texas" was Hunter's father, L.M. (Kit) Carson . . .

Mary Louise Weller, who's previously been most visible as a campus queen in "Animal House" and Chuck Norris' girlfriend in "Forced Vengeance," will tackle a meatier role when she stars in a slightly revamped version of "The Wild One." Weller will play the Marlon Brando role, an individualistic motorcyclist . . . And Debra Winger -- who was signed to star in "Peggy Sue Got Married," stayed with the project when actress Penny Marshall was appointed director, threatened to walk out when Marshall was removed, returned to the role when Francis Coppola was chosen, and then got sick and had to cancel -- has officially been replaced by Kathleen Turner. She's been involved in some tangled situations of her own in negotiations for "Jewel of the Nile," the "Romancing the Stone" sequel.