Washington Post wrote:
TEHRAN — Whenever an Iranian blogger, connects to the Internet from his office, they switches on a special connection that for years would bypass the Islamic republic’s increasingly effective firewall.
But recently the software, which allowed them to go online through portals elsewhere in the world, stopped working. When it sporadically returns, speeds are so excruciatingly slow that sites such as Facebook become unusable.
[SNIP]
Many fear that the disabling of the software used to bypass the state-run firewall heralds the coming of what authorities have labeled the National Internet. The government’s technology officials have announced the construction of a domestic Internet network comparable to an office intranet, which would block many popular sites. They have hinted the National Internet can be launched at any time, and have said it will gradually start working over the coming three years.
[SNIP]
“They are stealing people’s information and following their own … goals,” said Reza Taghipour, the communication and information technology minister, when speaking about foreign governments and online companies in January. “We need [the National Internet] to protect the privacy of families.”
[SNIP]
“Basically they are already shutting off access to all interesting Web sites,”
“We will resemble an isolated island in a changing world if this happens.” Said an Iranian Blogger
[SNIP]
An assistant in a printing house, said he said bade farewell to the Internet last week. “None of the fun sites such as Facebook work anymore. All I can read is official Iranian news Web sites,”
“Now I devote myself to work, only work. No Internet.”
Read the rest of Story in WashingtonPost: Iran increasingly controls its Internet
Also more About Iranian Internet: http://en.wikipedia.org/wiki/Internet_censorship_in_Iran
In October 2006, the Iranian government ordered all ISPs to limit their download speeds to 128kbit/s for all residential clients and internet cafes. Although no reason for the decree was given.
Update: As of Feb 9, 2012 Instant Messenger and Emails services and many other SSL enabled services has become inaccessible in Iran.
Update 2: Tor Project now confirm the blocking: Iran partially blocks encrypted network traffic
Update 3: PC Magazine talk about this too: Iran Reportedly Cuts Off Access to Secure Internet Sites
Update 4: Mahsable says: Iran Reportedly Blocking Internet
Update 5: Heise Online says: Reports: Iran disrupts secure internet connections
Update 6: It seems government is lowering the blocking.