UPDATE at 2:00 PM EST
Iran has informed the IAEA that they will begin enriching uranium to 20% starting tomorrow.

UPDATE at 1:24 PM EST
Iran's supreme leader has threatened violence if planned opposition marches lead by Mir Houssein Musavi are carried out this week. Iranians will "punch [them] in the mouth to shock them" Ayatollah Khamenei promised -- though he demurred over who "them" is -- the protesters, their leadership, or the "western puppet-masters" he claims are instigating their "counter-revolutionary" behavior.

News on Iran's next move continues below.
From Reuters India:

TEHRAN (Reuters) - Iran will soon unveil a domestically-made air defence system with at least the same capability as Russia's S-300 anti-aircraft hardware, an Iranian air force commander was quoted as saying on Monday.