A new book by Evgeny Morozov called "The Net Delusion: The Dark Side of the Internet" shows how authoritarian regimes such as Iran and Belarus can use the Internet to further their own aims and increase repression.
In one of his interviews at this site, Morozov notes how there was a great deal of enthusiastic response to protesters in Iran using the Internet to report on what was going on and to promote demonstrations after elections there. However the media gave little coverage to the consequent use of the same Internet communications to seek out and often arrest those who had been promoting the protests.
Morozov examines the use of the Internet in countries such as Russia, Belarus, China, and Iran and finds that governments can use Internet information to threaten dissidents. In some cases he suggests that there are government sponsored cyber-attacks on dissident websites. As well, governments use the Internet to promote their own agendas. While censorship is one means of controlling Internet content Morozov thinks that it is a mistake to think that this is the only means that governments can use to control the Internet.
There is also an interview with Morozov here and also here. All three videos can be found at this site.Morozov is a visiting fellow at Stanford University in California.