This is from Diablo3.com's front page about what the announcement is not.
"Things the May 1 Announcement are not:
1. It is not an official announcement of Diablo 3
2. It is not about an upcoming Diablo novel
3. It is not a Network merge"
Also there is this
"We do have our own set of theories such as the Blizzard Worldwide Invitationals ending the same day Diablo II was released (June 29 2000) and Diablo II: Lord of Destruction expansion being released (June 29, 2001)."










