This time, I can probably make it simple. Ahmadinejad made a big mistake by pulling the Basij into this. The arresting, shocking footage was exactly what the protesters needed to make this whole thing about their struggle. Whether Mousavi or Ahmadinejad won the election is almost immaterial at this point: the repression itself is stripping away his legitimacy.
There are two things to look out for right now: the army, and the 'net. The question of whether or not the Army is going to get involved looms over this whole thing. They said they were "neutral", but I've read accounts implying that there's some internal strife going on there, and it may well continue. Conflict within the army makes it far harder to turn them against others, however, so that may be good news for the protesters in-and-of itself.
Whether they'll be able to keep up connections with the outside world is a better question. You've probably already seen #iranelection practically turning on itself from fears of Iranian monitoring, and that's going to keep up. That may scare away actual Iranian twitterers, and lets be honest: they're the story here, not the rest of us. But there are indications that it's getting harder and harder for Mousavi supporters to get online, period, or even carry around a laptop without getting it smashed. Will Iran slowly go dark over the next few days? And can anybody do anything about it?
I hope enormously that it doesn't go dark. That may be the only thing preventin harsher repression. Those cameras and "tweets" need to stay on.
Tomorrow (Tonight?) is the strike. We'll find out the answer to the military question, at least. And, I suppose, we can move on from there.