Blizzard did, apparently. As a few emailers and forums posters have noted, Diablo III is now showing as a title on many a Battle.net account. It’s not playable, and it’s not even beta access, sadly. Just a sort of advertisement to remind you of a future digital purchase.
So enjoy the sight of Diablo III on your account.. just don’t get too excited yet.
Update: As several commenters have testified, and as was already made clear in the original forum thread, this is not dependent upon a valid WoW subscription or on the “12 months of WoW = free digital D3.” Diablo III is showing up on the accounts of people who have no WoW access whatsoever.