Ahmedjitiot and his minions have made tons of outrageous claims and threats. I'm more concerned about actual threats, like their involvement with Hezbollah and nuclear ambitions. I am less worried about dates and crazy predictions from a bunch of Nostra-dumbasses.
My guess on the August 22nd thing is that Ahmedinijad (sp?) and the Iranians will try to test some sort of nuclear device on that date so that they can officially declare themselves a nuclear power.