The three day-long exercises reflect the Iranian regime's misgivings about the mounting domestic unrest in the capital. During a much-anticipated Friday sermon, Ayatollah Ali Khamenei revealed his suspicions of a foreign role in the protests. Tehran may be wary of Israel, or even the United States, using the current turmoil to attack its nuclear facilities or make an attempt at regime change. The "Birth of Light" is an act of "swaggering", if you will, where Iran shows off its military abilities to demonstrate a potentially staggering cost for any possible act of military intervention or foreign-endorsed domestic subversion.
This is probably the kind of thing Obama had wished to avoid, when he warned against perceived "meddling" in Iranian politics. The Iranian regime is likely to ratchet up the rhetoric and intensify belligerent actions to thwart what it deems a foreign-engineered coup.