The report from Der Spiegel:
New simulations carried out by European Union experts come to an alarming conclusion: Iran could have enough highly enriched uranium to build an atomic bomb by the end of this year....
For one scenario, the JRC scientists assumed the centrifuges in Natanz were operating at 100 percent efficiency. Were that the case, Iran could already have the 25 kilograms of highly enriched uranium necessary for an atomic device by the end of this year. Another scenario assumed a much lower efficiency -- just 25 percent. But even then, Iran would have produced enough uranium by the end of 2010.
Earlier this month, the New York Times reported on a new, more efficient centrifuge that the Iranians had installed in their facility at Natanz:
Experts said Iran's design for the IR-2 centrifuge showed considerable technical creativity.
In an interview, a senior European nuclear official who monitors the Iranian program said the IR-2 was "more ingenious" than its predecessor, an unreliable machine called the P-1, with the "P" reflecting its Pakistani origins. The official insisted on anonymity because of the political delicacy of the issue.
It does not appear that this simulation accounted for these "more ingenious" centrifuges. As Eric Hundman explained at FP Passport, these new centrifuges are "not proof that Iran is pursuing nuclear weapons, [though] perfection of the IR-2 could make a nuclear 'breakout' scenario more feasible in the medium term."