Iran frees Roxana Saberi

I don't claim to have an idea why the Iranian regime decided to free Roxana Saberi, the Iranian- (and Korean-) American journalist who was arrested in January and then charged with and convicted of espionage. As this Register editorial notes, however, it is genuine cause for celebration. I know only a few things I have read and haven't had a chance to talk witrh anybody with special expertise. My guess is that international pressure, especially from European countries with which Iran has a certain amount of trade, was the key. But it could be internal Iranian politics or any of several other possibilities -- not including a change in character of the Iranian regime. I'm certainly glad for her, but whether it has geopolitical significance I just don't know.