I personally don't think they will, at least im not so sure. Ive stopped following the topic for a few months, but as ive loosely heard, Russia is willing to invest in their Nuclear energy plan, which gives me reason to believe America just wont be able to do anything about it, wen its only worthy oponent in the G8 is gonna back Iran up, with a diplomatic cause.
On the other hand, if US does attack Iran with the same phony reasons they had for Iraq, it will be a disaster... with their useless army, and Democracy that they supposingly bring, while they themselves don't have it, they'll just make the world even more mad, and their own people too.
BTW:
I stumbled upon a selection of pictures of Iran just now, while browsing another forum..
http://www.irandefence.net/showthread.php?t=32
It shows what the country looks like beyond wat the american media dictates. It suprises me that so many people in US are prolly paranoid and hatefull to nations like these... just because.