World's biggest diplomacy jamboree starts in NYC

The United Nations General Assembly this week will draw heads of state, foreign ministers and other leaders from at least 123 countries -- one of the busiest sessions ever, according to UN Secretary General Ban Ki-moon.

Ban cautioned, however, that the "general debate" held Tuesday through Oct. 1 comes at "a time of turmoil and transition."

There will also be confabs on Iran's nuclear program, the escalation of violence in Syria and hot spots in Africa, among other global issues.

President Barack Obama, will be the second speaker Tuesday after Brazilian president Dilma Rousseff.

Iranian president Mahmoud Ahmadinejad will address the assembly meeting on Wednesday, which is coincidentally Yom Kippur.

Obama is not expected to meet with Israeli Prime Minister Benjamin Netanyahu (although Secretary of State Hillary Rodham Clinton is expected to meet with him and other world leaders). Netanyahu will speak on Thursday, as will Palestinian president Mahmoud Abbas.