ProjectBlackstone.com late last year, and fans wondered if maybe it might be related to the mysterious upcoming Blizzard project code-named Titan. But no such luck, it seems: The domain went live this week and, soon after that, some crafty Redditors found the password. (It's "Y7_$0>0k_3<$m," if you want to try it yourself). The whole campaign has been revealed as a Starcraft 2: Heart of the Swarm tie-in.
Opening the site up reveals emails between various Terran characters talking about experimenting on Zerg lifeforms and presumably we'll see updates in the future that will fill out the story heading into the new game. Heart of the Swarm, the second part of the trilogy that Blizzard's Starcraft 2 has become, is due out on March 12.
[Thanks to everyone who sent this in]