I read on a futures forum that the Russians left the Bushah nuclear plant in a hurry. The speculation is that they have been informed of an attack coming from either the US or Isreal. I think they must have read some of Bush's speeches in the newspapers.
We need to look for weapons of mass destruction, etc., and so on, in Iran.
I doubt seriously that the U.S. has plans for an invasion of Iran in the near future. Both the invasions of Afghanistan and Iraq were well telegraphed. Sneak attacks are not President Bush's style, unless there was evidence of an impending threat from Iran, which there doesn't seem to be at the moment.
Israel, on the other hand, may have plans. Their intelligence in the region is greater than ours, and Iran poses a greater threat to their nation than to ours. Even so, I doubt that they would telegraph news of an impending attack to the Russians, if one were pending. It would give the opportunity to Iran to beef up their air defenses.
It could simply be that Russia has perceived some threat to their workers' safety, perhaps from Iran itself, and withdrew them for that reason.
Of course, it could also simply be an erroneous rumour, and the workers could still be on site.
V/R
Shapley