Iran, Centrifuges and the future of a dead-end relationship
I believe that Iran's new announcement of installing 6000 centrifuges is another step by hardliners in Tehran to show their determination and defiance against in the international community to stop enriching uranium at the time they think nothing can threaten them-- also another step forward to produce nuclear fuel.
On the other hand, they are simply trying to show their upper hand in their struggle with the United States. Iranians know that the US is not in the position to attack them or harm them seriously through pointless efforts like sanctions. So, their manouver over the nuclear program particularly is designed to show Americans that where they are standing. (read more about this story here.)