In the United States and in most of the world, the "right to blog" is pretty much taken for granted. You can say what you want whenever you want --no matter how outrageous. We blog for fun. In some places blogging can be a way to express dissent, even at great personal risk.
Try going to the site of Iranian blogger Sina Motallebi. What do you see there? As part of a crackdown on dissent in any form, Motallebi became the first blogger to be put in prison. Freed after three weeks, it seems the message is clear: criticism of the Iranian government or the clerics who run it in any form can mean prison.
The biggest fear of totalitarian governments is the free exchange of information. Iran was fairly successful in eliminating satellite television since the dishes are obvious. But communication via the Internet is harder to control. For an interesting article, take the time to read Cyberdissent: The Internet in Revolutionary Iran found here.