The most popular torrent file for StarCraft II has been downloaded 2.3 million times. For a game that weighs 7.19GB, that amounts to around 15.77 Petabytes of data downloaded. On August 9, TorrentFreak reported that the total number of pirated copies of StarCraft II totaled 260,000, making it the most pirated game of 2010, and we wouldn't be surprised if it has maintained that title as well. By comparison, Blizzard sold 1.5 million copies in the first 48 hours and 3 million by September.
Interestingly, BitTorrent has actually helped Blizzard attain those sales. The company uses its own BitTorrent-based client to deliver digital downloads to paying customers, effectively reducing load on its servers. It's also worth noting that the company has downplayed piracy as a significant problem. "For World of Warcraft, we have been able to work well around the piracy issue and we think we'll be able to do the same with StarCraft II," Blizzard told MCVUK, pointing to the new Battle.net platform.
As you've undoubtedly heard, StarCraft II doesn't support LAN, so pirates only get the single player experience -- and a diluted single player experience at that. Progression milestones like achievements are only available with a Battle.net account and an Internet connection. With multiplayer being the focus of the game, one has to wonder how many of the 2.3 million illegal downloads have translated to legitimate sales, especially since Blizzard doesn't provide a free public demo of the game.