Information continues to make it out of Iran thanks to Twitter and people setting up proxy servers. Unofficial information sources are nothing new, it's just the sheer volume of people who have access now. For those of us who used to social network via CB, HAM and radio teletype, fresh first hand information was easy to come by. A large city may have had a few thousand HAM radio operators and maybe a few radio teletype operators. Most were easily found and shut down. There were always a few that were able to stay a step ahead of the government. Today there are millions of people carrying cell phones, a hand held device that has replaced what used to occupy an entire desk top, and that big tower in the back yard. And thanks to services like Twitter, with numerous access points, it is almost impossible to shut down.
The Iranian government has it's hands full and it looks like they are loosing the communication battle, at least for now.