Unfortunately, it looks as if one of the best twitterers of the Iranian dissent has been grabbed by the security forces:

’# I heard about @PersianKiwi I have no idea how they captured him/her, he/she was using freegate I guess
# I don’t think if gov really captured PersianKiwi, they knew about his/her twitter & hopefully will be released soon
about 16 hours ago from web
(From ‘Change _for_Iran’)

Its what I feared - he’s not tweeted since Wednesday last week, and it makes sense in view of this headline today:
Iran ‘has arrested 2,000’ in violent crackdown on dissent