Blizzard has never committed to releasing a game on Linux because they have always felt it was not commerciually viable in today’s market, but the mood could be changing.
According to a source at Blizzard, there could be a linux game release this year from the studio. With Windows 8 not exactly proving popular with developers, Blizzard sound like they could be ready to take the plunge, although what the game would be is unknown. Perhaps Starcraft 2, World of Warcraft or even Diablo 3? Your guess is as good as ours.
Blizzard has worked on a Linux version of World of Warcraft internally which has never been released due to the fact that the game works fine under WINE, despite bannings of accounts using WINE which were wrongly accused of hacking.
Blizzard has always been a staunch supporter of the Mac so could they be adding another OS to their supported list? Apparently we should find out more this summer according to Phoronix.