Iran is far from a free and open society, but apparently its control of the Internet is not as pervasive as one might think.

Created by the OpenNet Initiative (ONI) -- an Internet surveillance monitoring partnership between the Citizen Lab, the Berkman Center for Internet & Society, the Advanced Network Research Group at the Cambridge Security Programme, and the Oxford Internet Institute -- this week's Tuesday Map plots the top 6,000 Persian language blogs according to the links among them, showing both those blocked (left) and visible (right) inside Iran.

Each dot represents a blog, color-coded by content (yellow and green for reformist, secular and expatriate bloggers; purple for Persian poetry; green for popular culture, and red for religious and/or conservative bloggers) and scaled by the number of links to the blog from other sites. 

Although most blocked blogs are "secular/reformist" in nature, ONI notes:

[T]he majority of these [secular/reformist] blogs are not blocked. Also, a handful of blogs from religious, pro-regime parts of the network are blocked as well. A preliminary analysis of these indicates content (like anti-Arab bias and discussion of "temporary marriages") that, while not unfriendly to the Islamic Republic, might nevertheless be embarrassing to it."

For a closer assessment of the Iranian blogosphere, check out this more detailed map and case study from the Internet and Democracy project at the Berkman Center.