Final words of a good analysis piece in today's New York Times entitled In Iran, an Iron Cleric, Now Blinking:
"Everyone speaking of Ayatollah Khamenei tends to use the word 'cautious,' a man who never gambles. But he now faces a nearly impossible choice. If he lets the demonstrations swell, it could well change the system of clerical rule. If he uses violence to stamp them out, the myth of a popular mandate for the Islamic revolution will die."