Update, 5:36 p.m.: Gooya News has a bunch of pictures from today.
And the New York Times has some more video up from today. They're also reporting that protesters went back to the rooftops in Tehran around 11:00 p.m. local time to resume the nightly chants of "Allahu Akbar." Remember, protesters did this in 1979, during the Iranian revolution.
Update, 3:47 p.m.: An account from the AP -- this is from a protest on Vali Asr Street, the main north-south drag in Tehran:
Women in headscarves and young men dashed away, rubbing their eyes in pain as police fired tear gas, in footage aired on state-run Press TV. In a photo from Thursday's events in Tehran obtained by The Associated Press outside Iran, a woman with her black headscarf looped over her face raised a fist in front of a garbage bin that had been set on fire.
Update, 3:43 p.m.: We're hearing some credible reports of an attack on Amir Kabir University, a science and technology school in Tehran. Armed militiamen broke into dorms and assaulted students and guards; they also allegedly destroyed dorm rooms and classrooms. No idea how many students were on campus at the time.
Update, 2:39 p.m.: More video. It's shaky and only 19 seconds long, but you can see easily a few hundred people in the crowd.
The Los Angeles Times has its own rundown of the day's events: businessmen hiding protesters in their shops, riot police using tear gas, a woman being beaten.
Update, 1:57 p.m.: The BBC Persian service has a gallery of photos from today.
Update, 1:22 p.m.: A few images starting to trickle out, too.
Lots of reports on Twitter, including several from people I trust, that the protesters are chanting not just "death to Khamenei" but "death to Mojtaba" -- Khamenei's son. That's an interesting development, considering the article in The Guardian earlier today that claimed Mojtaba is in control of the Basij militias.
Update, 1:15 p.m.: I heard a lot of talk earlier today that Mousavi would make an appearance at today's rallies. So it's worth asking: Where is he? It's 10:00 in Tehran already, so he's obviously not going to show up -- is there a reason why?
Update, 1:01 p.m.: Another short clip that also appears to be from today.
The protesters have been regrouping on side streets -- with some success, it seems -- since they were turned away from Enghelab Square. Still only a few thousand protesters, but in larger groups now. The New York Times has a decent summary of the events so far.
Update, 12:41 p.m.: The usual caveats apply about verifying video from Iran -- but this seems to be from this evening's protests.
Update, 11:12 a.m.: Here's a Reuters report on the protests at Tehran University.
Iranian police used tear gas and fired into the air to disperse about 250 pro-reform protesters gathered near Tehran University on Thursday... "police used tear gas twice to disperse the crowd. There was also many Basij militia on motorbikes patrolling the area," said the witness, who asked not to be named.
Another witness said police urged passers by through loudspeakers to leave the area.
Also, Tehran Bureau is reporting that mobile service is down in parts of Tehran.
Update, 10:53 a.m.: Small groups of protesters are making their way to Vali Asr Street, the main north-south road in Tehran. Interesting how decentralized today's protests are -- a lesson from previous protests, perhaps.
We've also heard reports that the protests in Shiraz have turned violent, with Basij militiamen throwing protesters off a pedestrian bridge.
Update, 10:40 a.m.: Also worth stressing there seems to be a big IRGC (Revolutionary Guard) presence in the streets. Riot police too -- but the regime is sufficiently concerned about more protests that it dispatched IRGC troops.
Update, 10:29 a.m.: One point worth emphasizing: These are very small protests -- a few hundred protesters each, maybe 2,000-3,000 or so in aggregate.
Update, 10:18 a.m.: We're also hearing about protests in Shiraz (confirmed) and several other Iranian cities (unconfirmed). The Tehran University protests are a bit violent -- tear gas, batons, arrests -- but not the ones in Enghelab Square, it seems.
Update, 9:50 a.m.: The BBC is reporting that riot police used tear gas to disperse 200-300 protesters who were converging on Tehran University.
Update, 9:27 a.m.: Reports of a few hundred protesters moving towards Enghelab Square, but Reuters says they're being dispersed by riot police; other reports of a small number of protesters gathered around Tehran University.
Original post, 8:44 a.m.: Not much happening in the streets of Tehran right now, it seems, partly because there's a huge police presence. We're hearing reports of thousands of police and plainclothes Basij militiamen on the streets, particularly around Enghelab Square.
You'll remember that the regime used the same strategy, starting about 10 days after the election, to finally break up the protests. Throw enough police on the streets and it becomes impossible for people to gather.
More news as we get it.