Following on from my previous post about how to use a Greasemonkey script in Firefox to auto-translate Persian tweets in Twitter here's another way to get Persian tweets into English. The Google System blog has a good overview of how to do this but you're here, and this can be a little clearer.
Go to Google Translate and copy the following string of text http://search.twitter.com/search?q=%23iranelection&lang=fa (it's searching for tweets with #iranelection in Persian) into the search box...
Twitter's front-end interface doesn't give you the option of searching only Persian/Farsi tweets, but the search does seem to support it by adding lang=fa to the query string.
Sadly the AJAX updater won't tell you if new tweets have come in since you've been looking at the page, but you can just refresh your browser and it should pull out any new ones.
And you can get a Google Translate button for your web browser here. Once you've got the button, just click it whenever you have Persian text on a page and it'll translate it for you.