Carnegie Hall is keeping Aprile Millo's concert a little secret. Their flash-website lists only that La Millo is occupying their Isaac Stern Auditorium on October 14, while their text-only website gives us an additional bit of info: "presented by Ron Delsener." Ron Delsener, of course, is the preeminent rock promoter, whose past and current clients include every imaginable major pop act of the last quarter century (from the Beatles and Barbra Streisand to Coldplay and U2). Meanwhile, in breaking-news fashion, La Millo's own intrepid promoter wrote an eager post on opera-l confirming that Delsener is organizing the "unique and historic" event, details of which "have yet to be finalized." But wait, a check on Ron Delsener's official website lists three Delsener concerts that evening (The Fiery Furnaces at Town Hall, Stephen Lynch at Westbury, and U2 at Madison Square Garden) but no mention of Millo, Carnegie Hall, or "rock." Sieglinde, hungry for diva and for more details, shall nonetheless purchase tickets (available August 26) to this mysterious event, are you kidding me (but checks her Visa card account online, just in case ...) Unique and historic, indeed ... probably other adjectives too.