The website of curse has reported that the "countdown teaser" of Diablo 3.

The rumors surrounding Diablo 3 have been revived yet again. This time it's Blizzplanet a Blizzard fansite who is the source. Since Blizzplanet is known to have friendly ties with Blizzard, it's likely to be something interesting and certainly not a hoax. The countdown ends on May 1st. It currently (at the time of me submitting this news) show a 12 days countdown.

Read More: Diablo3.com Countdown

The post on diablo3.com leaked more details about the countdown teaser. 

In the past days there have been a lot of activity in the network sites after the countdown teaser. A few forum threads keep continuous debate between Diablo fans of what this announcement will be. I have given a few responses of what it is not, to make sure fans won't be thinking the wrong thing. We have made no claims and expect fans to not get caught up with the wave of speculations and rumors in the forums and the web to the point to believe them.

What the flip is the May 1st Announcement then?
Well, the answer will be unleashed that day. Not earlier.

Does Blizzard know?
I would say yes.

Read More: Here