Iranian Internet has slowed down massively over the last ten days, and is down to 5Kb/s. More and more websites and social networking sites (Facebook, etc) are filtered. One of our Observers, Sara M. (pseudo), a student in Tehran, managed to send us a short video in which she shows how state censorship works on the Web and on text-messaging services.
To find out more about censorship of the Web, we recommend this article in the Wall Street Journal. It explains how filtering technologies used in Iran were developed by European companies Siemens and Nokia.