Twitter's Double-Edged Sword In Iran?

Time's Lev Grossman reports there are widespread rumors that the Iranian government is using Twitter, which has delivered vast quantities of unconfirmed information to the rest of the world about what's going on in Iran, to its own advantage as the turmoil unfolds:

Rumors of the Iranian authorities' tampering with Twitter traffic are rampant. But very little hard data is available, and so far it's not clear that they've throttled Twitter completely. Why not is a matter of great speculation. It's quite possible that the government finds Twitter useful as a way of monitoring protesters, gathering data on them and even tracking them down. There are also signs that the Iranian government may be infiltrating the Twitter network itself, manipulating it to its own advantage. This tweet went out over the network earlier today, and was itself retweeted more than 200 times:

DO NOT RT anything U read from "NEW" tweeters, gvmt spreading misinfo

("RT" stands for re-tweet.)