Iran, whose authorities employ a variety of methods to impose tough Internet censorship, had seen Facebook unblocked in February.
Since then, an increasing number of Iranians inside the country have turned on to Facebook, to keep in touch or exchange information.
There is a whiff of irony in the fact that President Mahmud Ahmadinejad has several fan pages on Facebook. On one, he has about 7,000 fans from several Muslim countries. (Ahmadinejad detractors have meanwhile created a Facebook page that has attracted 40,000 fans and boasts, "I bet I can find 1,000,000 people who dislike Mahmoud Ahmadinejad.") But he had not been campaigning there in the narrow sense of the word.
Both reformist candidates, Mir Hossein Musavi and Mehdi Karrubi, have accused the Iranian state broadcaster of biased election coverage that favors Ahmadinejad.
Musavi supporters have used Facebook extensively -- and effectively, according to ILNA -- to promote him and his ideas. (Musavi is said to have his own Twitter account.)
Karrubi backers have put Facebook to use, too, to spread their candidate's views, albeit to a lesser degree.
On its surface, then, the blocking of Facebook looks like a government-inspired move to limit campaign-boosting activities among Ahmadinejad's challengers, since the incumbent has crucial support within effective dissemination tools like the Islamic Revolutionary Guards Corps and the state broadcaster.
It would be a particularly egregious move if you're among those who believe that voter apathy is key to an Ahmadinejad victory.
-- Golnaz Esfandiari