There can only be two purposes behind the recent post-election Stalinist style show trials in Iran:
1)- Iranian regime is trying to distract the world from its crimes, and 2)- The mullahs are trying to scare their own people and prevent further uprisings.
I am not sure about the first objective they are trying to achieve because the mainstream media won't report what they don't see and therefore the world won't be able to see much either. However, as for the second objective has already failed. We are no longer afraid of this murderous regime. They're scared of us. (Europeans condemn the show trials).
Updated: Check this image. A lot of Iranians are unhappy with what Obama and his team have said. They're specifically upset with Obama's dumb spokesman saying that Ajad is the 'elected leader' of Iran.