AND NOW HERE'S THE NEWS: Speaking of Petty, the pop star's new album, titled "Let Me Up, I've Had Enough," is due out April 20, featuring a new single, "(Stop) Jamming Me," penned by Petty, Mike Campbell and Bob Dylan. The popster has tentative plans to tour later this summer. . . . Everyone is doing cover songs these days (including such current hits as Bruce Willis' "Respect Yourself" and Club Nouveau's "Lean on Me"). And judging from the British charts, there are more to come. Freddie Mercury (rock's answer to Liberace) has just released a remake of the Platters' "The Great Pretender," while Boy George (remember him?) has done a reggae-style remake of David Gates' "Everything I Own." . . . And speaking of cover songs . . . Southside Johnny & the Asbury Jukes have just finished filming a pair of songs, including the 1967 Soul Survivors hit, "Expressway to Your Heart," which are slated to appear in the upcoming Disney film, "Adventures in Baby Sitting." The movie, directed by Chris Columbus (who wrote "Goonies" and "Gremlins") is due out this July. . . . Pop music is always at the head of the class when it comes to cashing in on trends, so isn't it time for a "Safe Sex" anthem? Perhaps the first record to focus directly on AIDS, and its effect on sexual relationships, is a new dance music single called "Sex in the '80s," performed by Ghost, a group put together by producers Abram Maguire, Mark Shifman and Gio Vanelli. The song features a dance-club conversation by vocalists Denise Rene and Bernard Spears that touches on many of the problems associated with AIDS' impact on casual sex.