The tools that easily enable the organization of dissent are also being used by those in power to maintain control:

since that revolt collapsed, Iran has become a cautionary tale. The Iranian police eagerly followed the electronic trails left by activists, which assisted them in making thousands of arrests in the crackdown that followed. The government even crowd-sourced its hunt for enemies, posting on the Web the photos of unidentified demonstrators and inviting Iranians to identify them.

“The Iranian government has become much more adept at using the Internet to go after activists,” said Faraz Sanei, who tracks Iran at Human Rights Watch. The Revolutionary Guard, the powerful political and economic force that protects the ayatollahs’ regime, has created an online surveillance center and is believed to be behind a “cyberarmy” of hackers that it can unleash against opponents, he said.

From The New York Times