Not even an unfashionable downpour could deter New York City's style mavens from attending the April 26 Metropolitan Museum of Art Costume Institute gala (the theme was ''Dangerous Liaisons''), cohosted by Renee Zellweger, Vogue editrix Anna Wintour, and Asprey chairman Lawrence Stroll. With soaking trains in hand, busty belles such as J. Lo (who arrived with designers Domenico Dolce and Stefano Gabbana) and Charlize Theron enjoyed 18th-century art and 21st-century musical performances (by Hugh Jackman and N.E.R.D.), not to mention a little reverse star-gazing. ''I can't wait to meet Zac Posen,'' gushed Eva Mendes. ''I'm wearing one of his dresses!''