So much for all that talk about the ''mainstreaming of porn.'' Not in prime time, at any rate, where Fox has canceled ''Skin,'' its low-rated drama about a Romeo-and-Juliet couple set in the backdrop of the adult entertainment industry. Fox made the announcement Tuesday in a statement, one day after the show's third episode drew a paltry 4 million viewers (according to Nielsen estimates), losing out among 18-to-49-year-olds and overall audience members to the WB's family drama ''Everwood.'' The show's failure marked a rare misstep for Über-producer Jerry Bruckheimer (the ''CSI'' franchise, ''Without a Trace''), who has never been accused of making shows or movies that were too envelope-pushing or edgy for the mainstream, until now.
Bruckheimer's loss is ''Joe Millionaire'''s gain. Fox had pulled back on the low-rated second edition of the reality dating show, deciding to air it just once a week instead of twice a week during the all-important November ratings sweeps period. With ''Skin'' gone, however, from its 9 p.m. Monday slot, Fox will air new episodes of ''Millionaire'' then, preceded by its regular ''Joe'' installments at 8. Reruns of ''Skin'' that had aired at 9 p.m. on Thursdays will be replaced by new episodes of Fox's more successful teen romance drama, ''The O.C.'' Don't expect to see the remaining five unaired ''Skin'' episodes. '''Skin' will not return to the Fox schedule'' is all the network had to say about the show in its statement.