Over on the Fark Blog, Drew is postulating as to why Cuba would announce Castro's resignation at 3am:
I find the timing completely bizarre. Unless the government spokes-agency people had toddlers running around their houses and felt like getting some work done, there’s no good reason why the announcement couldn’t have waited until the morning. Was Castro up at 3am thinking to himself “damn this job sucks, I really should retire”? Not likely.He's most likely right, since that's an odd time to do such a historical thing. Discuss amongst yourselves...
The only valid reason to make an announcement like that at 3am was that the government was in a hurry. Something happened in the middle of the night to make them move up the timetable.
I’m going to go out on a limb and speculate that Castro is dead.