Ahmanutjob or Ahwannajihad, or whatever that shiite-for-brains moron calls himself, didn't promise anything in particular for exactly 12AM Iran time - we've still got 24 hours to go. I'd bet on an announcement sometime in the morning, GST (that's Goatphugger Standard Time), which'd be in the 11PM-2AM EST range.
I agree with BigFinn that they will probably announce that they've got nukes that they bought from either Pakistan or some corrupt ex-Soviet general, and that they've got them on missiles at 10 locations throughout the country, and that if the US or "the Zionist Entity" messes with Iran, then Iran will "obliterate" us (or some such nonsense). Either that, or that they have dirty bombs on their missiles, with the rest of the message the same. Either way, we're in for trouble.
I don't think that they've got nukes from their own production - it seems a bit early for that, though if 2 years went by with nothing done to interrupt the process I wouldn't be so optimistic (that's a HINT, George of 1600 Pennsylvania Avenue).
To announce or do nothing would seem completely foolhardy, even for this nut, so I think that we'll have a busy news day starting sometime late tonight.
Did you say 24? Only one person can save us now.