There is a word for this kind of date-linking rhetoric that eludes me at the moment. If you tell a group of people you're going to announce something on well-known day of religious importance (say if Bush made a big announcement on Easter Sunday), you are trying to appear as a prophetic authority. You are saying "Allah is with this decision" because we are doing it on this religious day.
Think about what just happened. A month before they're going to announce their decision on this offer, they force Israel's hand to do something devastating to basically neutral Lebanon. More than anything they want to split Israel and the West - and leave Israel isolated.
What will Aug 22 be? "SANCTION ISRAEL if you want us to stop our nuclear program. Jerusalem is our where our Holy Al Asqsa mosque is, and it is in danger. This is religious persecution. We our outraged. blah blah. PUNISH ISRAEL for their invasion, and we'll agree to some of your demands."
They want to FORCE A CHOICE between supporting Israel or having a succesful nuclear negotiation. This will be VERY TEMPTING FOR EUROPE. France is the weaklink in the support Israel chain, and Iran will hammer them with back channel rhetoric to lead Europe in turning their back on Israel for the sake of nuke deterrance.
France - "Do you want to support Israel (and its war) or do you want us to disarm our nukes?"
Maybe I'm way off on this, but Iran is so freakin devious it's scary. Their ability to blackmail through terrorist acts seems unparralleled since they started doing it in 1979.
http://en.wikipedia.org/wiki/Isra_and_Miraj
So all the rantings from Iran are just like a criminal gang leader yelling out of his house at the police who have him surrounded and are moving in to arrest him. The fun-sized psycho in Iran is deluding himself that somehow he's going to win a military confrontation against all the major military powers in the world. It appears to be difficult for these Iranian leaders to face up to reality. They are so used to calling the shots, telling everyone else what to do, and doing whatever they want in Iran, and now the big world powers are telling them "no, you can't build nukes." So far, they're in denial of reality and refusing to face up to the inevitable conclusion of this confrontation.