The No Line On The Horizon Tour started off at about the same time as the post-election protests in Iran.
U2 went green.
They showed their support of the Iranian people with stage lighting and songs.
The tour swings through the American southeast in October, and U2 continues to show their support of the Green Revolution. Will their audience still understand what they're doing?
Twitter no longer shows #iranelection as a trending topic. The Islamic dictatorship of Iran suppressed dissent with so much violence that the people are afraid to march. There is the very real danger of imprisonment and torture, without legal counsel or justice.
When the stage goes green every night in the giant claw stage set, U2 will remind their fans that the Iranians are still not free. Revolutions are not confined to the period of time that the topic is trending in the social media.