What happened to me, and what other people have reported as the normal sequence of events is:
1. When your file first goes complete, you get a complete date.
2. When a decision has been reached, your complete date changes and there is a message that says,
You may notice that your current status date has changed. This is either because a portion of your file has been updated or the initial review of your file has been completed. Neither of these situations change your early, regular, or late decision standing. We are unable to release decisions by phone or email. All final decisions will be mailed.
3. Shortly after the complete date changes and the above message is displayed (it was less than 24 hours in my case) the status changes to Decision Rendered.
4. You receive either a phone call or letter with the decision.
People who were both accepted and rejected reported the same sequence. The difference was that people who got accepted received a phone call within a day or two of the change. People who were rejected received a letter.
So it looks like a batch went out today... and I claim the title of
Nostradamus de April for predicting it

(And we'll just ignore my miserably incorrect predictions for the earlier rounds!)
Hopefully all who are waiting get phone calls soon!
Edited for clarity