The LA Times has some great reporting from today's protests:

According to one witness, who asked not to be identified for fear of reprisal, Mousavi stepped out of his car only to be surrounded by police, who forced him back into his vehicle and out of the cemetery. At first, mourners were confronted by security forces, who struck some with batons and made arrests in an attempt to bar them from gathering at Tehran’s Behesht Zahra cemetery, the country’s largest. [...]

The witness said protesters identified and violently confronted several plainclothes Basiji militiamen. “Police, police, support us,” the crowd chanted. “God is great!” But as people poured out of the nearby subway station and taxis along the highway, security forces retreated. One witness said police released detainees and began cooperating with the mourners, directing them to Section 257 of the cemetery, where Agha-Soltan and others were buried.

This is not over.