Its commercial prospects are still a big question mark, but when "9 1/2 Weeks" debuts tomorrow, the steaminess of its story and the strains of sadomasochism will have already made it as talked-about as any movie of the past year.

And as hard to release, since three studios once involved with the project backed off before MGM/UA picked it up. The film even gave one record company cold feet: Geffen Records, which was originally supposed to release the sound-track album, dropped the record because, said one executive, company execs didn't like the film.

Plenty has been written about the film's sex scenes and its systematic domination of Kim Basinger by Mickey Rourke. Suffice it to say that it's toned way down from the book and, apparently, from early drafts of the screenplay. But the movie's oddities extend even to more trivial matters, like its title. There's nothing odd about the phrase itself (which refers to the duration of the Basinger/Rourke relationship), but director Adrian Lyne pulled a switch when he transferred it to the screen. In ads, in press materials, on the cover of the original novella and virtually everywhere else, the title is "9 1/2 Weeks" -- but on screen at the beginning of the movie, it's "Nine 1/2 Weeks," a rather awkward mixture of straight numerals and spelled-out numbers. Role Reversal

There are two struggling singers, one an enormously successful ladies' man and one a timid sort who has never slept with any woman besides his wife -- who promptly leaves him in the first reel. The movie is Elaine May's "Ishtar," and the leads are played by Warren Beatty and Dustin Hoffman -- but according to a script uncovered by the Los Angeles Times, the two actors aren't exactly typecast in the planned year-end Columbia Pictures release.

Hoffman, it seems, plays the lady-killer; Beatty is his less amorously adept friend and, for a time, his student in the art of seduction. The movie, they say, also includes spies, a Morocco nightclub where the two singers work, a comely Mideastern lass (Isabelle Adjani) who falls for Beatty while posing as a boy, a secret map and lots of other stuff -- none of which should come as a surprise in a film that dares cast Warren Beatty as something of a nerd. Sneak Previews

"Ishtar" may be a top-secret production at this point, but the film exhibitors who traveled to Las Vegas for last week's ShoWest '86 convention got to see a small bit of the movie. The film was included in an extensive product reel shown by Columbia, promoting 16 upcoming and just-released films in an attempt to overcome the hard-luck image the studio had for much of last year.

But Columbia wasn't alone at ShoWest: All the studios were out in force, showing off new films and announcing upcoming productions, such as "84 Charing Cross Road," a Mel Brooks film with Anne Bancroft and Anthony Hopkins (Columbia); two yet-untitled films to be directed by "Out of Africa's" star and its director, Robert Redford and Sydney Pollack (Universal); a sequel to "The Breakfast Club" (Universal); and Clint Eastwood's "Heartbreak Ridge" (Warner Bros.).

What a difference a few months and some hit movies make: At last fall's National Association of Theater Owners convention -- also a gathering of exhibitors and distributors -- the studios were conspicuous by their absence, and the exhibitors loudly complained about the scarcity of good films. But that convention came on the heels of a remarkably disappointing fall, which gave way to a quite successful Christmas, a strong beginning of 1986 and, suddenly, a new visibility on the part of the studios. Best Picks in Britain"

Back to the Future" and "The Purple Rose of Cairo" may not have gotten Best Picture nominations from the American Academy, but they're among the top nominees in Great Britain, where the British Academy of Film and Television Arts (BAFTA) has announced nominations for its March 16 awards presentation. Those two films were among the Best Film nominees, along with "Amadeus," "A Passage to India" and "Witness," all released in 1985 in Britain.