Well Josh had tweeted that he was in Miami; and the Miami Herald is reporting in their "Scene in the tropics" section --
Josh Groban, who recently made a cameo on Fox's new series Glee, was at W South Beach's WALL lounge on Friday night. The crooner showed up late with a group of friends and a security crew, took two tables and sipped on Grey Goose and Patron well into the wee hours of Saturday morning.(Source)
I found this review of Wall (sounds like a nice place to kick back after a long day in the studio)...
Possibly the most exclusive address in Miami Beach, Wall Lounge is a 3,500-square-foot nightclub tucked neatly away within the ocean-front W South Beach Hotel on Collins Avenue.
An oversize gold sofa with room for 32 serves as the club's centerpiece, and its gold and black patterned walls, lacquered bar, Cappellini stools and copper mesh ceiling provide the flash and glam. But the real key to Wall's success is its operators—Opium Group, along with Nicola Siervo and Karim Masri, who between them have given us such premier South Beach venues, as Joia, Mynt, Hotel Astor, Quattro, and most recently, Mokai.