Fashion isn't all fabulosity—it's big business, too. That's the raison d'être of The Business of Fashion, Imran Amed's Web site devoted to the dollars and sense behind the seams, which celebrated its fifth anniversary last night with a party co-hosted by Phillip Lim and Julie Gilhart at Chelsea's Hôtel Americano. But guests were exploring the more playful side of the biz. A white board and camera was set up for the live-est of live-tweeting on the theme "What Do You Love About Fashion?" (Scrawl your answer on the board, take a photo in front of it, and tweet it to the world.) One thing to love: Fashion is a business with a packed party schedule. Fashion weekers' itineraries last night were so crazed that even Diesel honcho Renzo Rosso himself couldn't make it to the opening of the brand's new Black Gold store in Soho earlier than halfway through. When he arrived from the W party uptown, he had Johan Lindeberg and Jefferson Hack waiting for him on the sidewalk. Hack croaked out a greeting, having temporarily lost his voice. No time to recuperate—the train swiftly made its way to the Gramercy Park Hotel, where Claire Danes was hosting pal Narciso Rodriguez's celebration. While the designer himself greeted guests sipping a drink named after him ("I must have a Narciso!" one guest crowed), Gloria Estefan was coaxed onto the dance floor to shimmy along to her 1985 hit "Conga." The dance floor was packed, too, at Rodarte's bash at Acme, where generations boogied together. Ikram Goldman and Michelle Harper represented the adults—well, the sort of adult who'd pull up her Peter Pilotto dress and vintage YSL couture underskirt to delightedly reveal a pair of Pilotto panties, as Harper did—and Tavi Gevinson and Harry Brant, the under-21s. All in all, stress relief done right. Kate and Laura Mulleavy's stylist, Shirley Kurata, admitted that producing a show is so taxing, "sometimes we think, I can't wait for the show to be over so we can get to the party!" Speaking of relief: It was February 14, after all, and Colette, Araks, and the Ace Hotel took up that challenge with a V-Day "Sex Party" at Le Baron, where party favors included racy lip appliqués and arty condoms. (Careful! They were, according to the packaging, "NOT MEANT FOR USE.") The second floor in particular was elbow to elbow, with Terry Richardson and Jared Leto among the crowd. Leto also ended up at the Top of the Standard's erotic-themed bash, which paused at 1 a.m. for a crowd-pleasing striptease by Dita Von Teese that ended with her doing a wet frolic in a giant martini glass. Just another night on the job. Her business is pleasure.—Matthew Schneier (BoF, Rodriguez, Rodarte) and Darrell Hartman (Diesel, Colette, Standard) read more..