call me simple-minded, but I suspect Iran's interest is fairly straightforward.  they've noticed that the US doesn't invade states that have a nuclear arsenal (even a small one).  they've noticed that the US does invade (and interfere with) states that control large oil reserves.  they don't want to be invaded or interfered with, so they want to have nukes.

I can't get past the underlying assumption of much of this discourse, which is that -- to put it crudely - n*gg*rs shouldn't be allowed to have guns.  why is it acceptable for a rogue state like the US to bend other states to its will using the implicit threat of nuclear strikes and the explicit strategy of carpet bombing, yet totally unacceptable for Iran or other ex-colonial countries to own nuclear weapons and negotiate from a position of partial strength rather than abject inferiority?

nuclear weapons are an insane technology to start with.  the size of the US nuke arsenal is evidence of some kind of psychosis (how many times over do you really need to kill every human being on earth, anyway?).  so for me the question of the double standard cannot be ducked.  Iran is a nation plagued by an unstable and repressive state dominated by religious and nationalist extremists.  so, increasingly, is the US.  of the two, the US has committed more recent aggressions, and is currently governed by an zealot-elite whose published documents (PNAC etc) espouse global empire as a desired goal.

it seems pretty clear that the only reason "we" don't want Iran to have nuclear weapons is because we plan to do a bit of B&E and GBH in the near future and would rather the householders were not armed.  my $.02...  that's what at least some of the players are after.

The difference between theory and practise in practise ...