The digital revolution is spreading across the wine world — whether the industry is ready or not. More than 450 wine-related applications are now available on the iPhone and other mobile devices — more than six times the number that existed only 18 months ago, according to a recent survey. Last year, people on Facebook, Twitter and other social media had 14 million online conversations about wine, providing recommendations, reviewing vintages and suggesting the best wineries to visit, said Paul Mabray, chief strategy officer for VinTank, a Napa consulting firm.