On July 17, thousands of supporters of reformist presidential candidate Mir Hossein Musavi gathered for the Friday Prayers in Tehran led by influential former President Ali Akbar Hafshemi Rafsanjani. Many were turned away by a massive security presence, but others rallied to show their rejection of the presidential elelction results, as you can see from the video below:
Musavi was widely expected before the sermon to be planning to attend. According to this photo on the ISNA news agency website, he did attend the Friday Prayers.
Meanwhile, another video shows Musavi supporters turning their wrath on a country seen to have backed President Mahmud Ahmadinejad's election victory, Russia: