Yesterday's major protests in Iran were cancelled because the opposition leaders feared a serious retaliation from the regime. However, some protests went on anyway, and there was a large amount of street fighting between protestors and the basiji vigilantes, with the police arresting people from both sides. I'm not sure what the specific consequences people feared were; there have been thousands of arrests by the regime, and the prisoners may have been involved somehow, or they may have threatened to step up the level of violence. I think for the resistance to be effective the students need to do more to support the reformists in Parliament...when the different reform-minded groups work in concert, as they do on prison sentences and such, they are far more effective than when the students take the radical line they have lately.
UPDATE: Hossein Derakhshan reports that major blogging sites are now blocked in Iran.