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?