There are many great arguments to protect truly private communications from a human rights perspective, and specifically through a Constitutional lens -- restoring the privacy of having a conversation in your living room and having your personal records stay personal are core first and fourth amendment rights which have suffered greatly in the digital age.

My work takes me around the world to support journalists, human rights activists, and a wide variety of amazing people working to improve the world. They are all facing incredible threats posed by powerful actors. These adversaries use malware, hacking, and all forms of digital attacks to compromise the networks of activists.

Open source, trusted, strong cryptographic tools -- and increasingly, trusted commercial systems such as Google's -- are their only available defense, in situations where failure can include targeted harassment, indefinite imprisonment, torture, and even death.

Encryption saves lives.

iRevolution has a good, academic-style breakdown of challenges and communication technologies for use to communicate securely within repressive regimes:

http://irevolution.wordpress.com/2009/06/15/digital-security/

It covers a lot of ground, balancing ease of use against level of security, and is looking for input!

The Daily Dish reposts a call to action from Twitter: ALL internet & mobile networks are cut. We ask everyone in Tehran to go onto their rooftops and shout ALAHO AKBAR in protest #IranElection, and comments:

That a new information technology could be improvised for this purpose so swiftly is a sign of the times. It reveals in Iran what the Obama campaign revealed in the United States. You cannot stop people any longer. You cannot control them any longer. They can bypass your established media; they can broadcast to one another; they can organize as never before.

Other coverage at Global Voices and Daily Kos present videos and links to photos of protests coming from Tehran.