That title might sound ominous, but this is not one of those emails (or forum posts) that points you to some trojan-infected malware site. You can legitimately download the full Diablo III installer, for most regions/languages, right now, from Battle.net. You can’t play it yet since this isn’t the game, and anyway, the servers aren’t live and you don’t have a valid CD-Key, but this way you’ve got the whole 7gig installer already set up, which will save you much time come 11:59pm, May 14th. At that point you’ll need to download the game files and install the whole thing, then pray the Battle.net servers hold up under the strain.Blizzard is providing the installers in advance to avoid the crunch of three million people try to download it at the same time, come May 15th. You’re given these links if you pre-purchase the game now, via the Blizzard store or if you got a free copy with your WoW Annual Pass. They’re useful for everyone though, even if you’re buying a boxed copy, regular or D3CE, since they’ll save you time by doing what used to be found on the “install CD” in advance.
Here are the codes so far available, all courtesy of this forum thread by SixPack. He’s vowed to update the thread with additional versions as they become available, so check back if your preferred region/language is not yet represented.
Post updated for technical clarity: thanks to info from some comments.