So far, only 10 arrests have been reported and some random thuggery by the usual regime suspects.

Former president Khatami has been involved in a physical altercation with the editor of a hard line, pro-Ahmadinejad newspaper. The older man was apparently unhurt as he has continued to march.

The British left wing newspaper The Guardian is once again live-blogging the event, picking up Twitter feeds and getting updates from on-scene Middle East correspondents. They have a couple of interesting videos including one that shows a massive crowd marching in downtown Tehran.

No reports from other cities yet.

This is kind of neat:

10.46am:
The Guardian's former Iran correspondent Robert Tait is monitoring events from Istanbul. He writes:

Ahmadinejad was giving a live interview on IRIB's Channel Two from the scene of Quds Day. As he spoke, viewers could clearly hear the chants of "Ahmadi, Ahmadi, resign, resign" - this all over live TV.

Apparently Ahmadinejad was aware of the chants and their effect on the interview. He is said to have become flustered and quickly wrapped up the interview.