You could feel the tension in the those rooftop chants in the anticipation for the events that will unfold today in Iran. From the Huffington Post:
A Facebook user named Seth Eslami posts a message on Christiane Amanpour's page: "So far I have received several goodbye emails from my friends in Iran. It's is sad...very sad & braking my hard.What is the price tag on freedom? We can't tell people what to do from here.I want to see them free but I hate to see them in blood..."
There are also reports of a buildup of security forces. From the BBC:
It is a very confused and tense situation. The security forces are out on the streets. They have been issuing dire warnings that they will deal with any unauthorised demonstrations with determination.
This is all about the position of the Supreme Leader. Any rally, particularly if it is attended by the opposition leaders, would be the most direct challenge to his authority. If it goes ahead and there is a large crowd, that would be a massive challenge to him. If it goes ahead and it is broken up with violent force, that could also damage his position enormously. It is a very tense situation. These are huge political issues at stake, if not even the future of the Islamic Republic.
Fire trucks took up positions in Revolution Square, the site of the planned gathering, and riot police surrounded Tehran University, the site of recent clashes between protesters and security forces, one witness said.
CNN recently tweeted the following:
Thousands of people attempting to enter Tehran protest site have been blocked by heavily armed police, eyewitness says.
Other tweets coming from people inside Iran:
Houses in alleys opening doors to injured protestors, one source reporting hallway is full of beaten ppl, many crying...#IranElection
Today is maybe the most important day in iran's history, will we see Tiananmen Sq.? It seems ppl don't care and still will go #iranelection
shooting reported in Azadi Sq.
Vanak Square reportedly full of civilian-dressed forces (lebas shakhsi)
There are current reports of tear gas being deployed in Azadi Square and police blocking protesters from entering. I fear we will be seeing some of the most disturbing images of these events after today is over.