And the big Grammy winner this year is . . . MTV? Sure, Carlos Santana appears poised to take home the most trophies at Wednesday's 42nd annual Grammy Awards, but a quieter success story will likely belong to the music cable channel and its flagship show, "Total Request Live." The program, known as "TRL" to its loyal viewers, has been ground zero for the 1999 explosion of teen pop and has become recognized as a potent industry launch pad for new stars. With a slew of nominations in major categories going to youth pop acts and other "TRL"-friendly artists this year, the show's host, Carson Daly, says "TRL" will enjoy even more prominence. "It will help give us the validity we've been looking for," says Daly, a former disc jockey for Los Angeles rock station KROQ-FM (106.7). "People have been talking about the phenomenon of the show and the impact [on music sales], but something as prestigious as the Grammys solidifies everything. . . . We're going to be like proud parents sitting there watching." And parents love family photos, which might explain why a dozen past "TRL" guests who got big boosts from the show--such as Britney Spears, 'N Sync, Christina Aguilera, Sean "Puffy" Combs, Jennifer Lopez, Goo Goo Dolls and Limp Bizkit--will gather today at a secret location in Los Angeles to be photographed for a "TRL Grammy Class of 2000" poster to be sold for charity. "TRL" will also set up shop in Los Angeles on Wednesday (giving a brief respite to Times Square in New York City, where fans create daily traffic snarls during tapings) for a two-hour Grammy episode. And what about rumors that Daly, who has become a teen heartthrob in his own right, may be mulling a departure from his "TRL" gig? "I'm not supposed to talk about it, but we're in negotiations now. . . . I'm very optimistic about [staying] and very proud of 'TRL.' "