The first really clear indication that serious planning was underway to strike at Iran's rogue nuclear weapons site came a month ago when British news outlets reported that Saudi Arabia had given Israel permission to cross its airspace en route to Iranian targets.
Yesterday, the United Arab Emirates ambassador to the United States said publicly that his country was willing to live with the consequences of a strike against Iran despite the enormous amount of trade between the two countries and the likelihood of riots after a strike.
Today, you have Sen. Joe Lieberman in Israel saying the U.S. would influence Iran, "through diplomatic efforts and economic sanctions if we can, but through military action if we must."
Now Lieberman is one of Israel's staunchest backers on Capitol Hill and is not commander in chief, so his comments can be taken with a grain of salt, but they also are a clear indicator that Israeli officials believe a strike is necessary. When the McChrystal fracas broke out, several senior retired and current military officers worried quietly that moving leaders at Central Command at such a sensitive time in Israeli-Iranian relations could leave the U.S. unfocused on a likely Israeli threat. The selection and rapid confirmation of Gen. David Petraeus alleviated some of those concerns but CentCom remains without a leader who has undergone Senate confirmation. While that may seem academic to many, Senate confirmation confers great credibility on a military leader and grants them wider discretion than an acting commander possesses, both in their own minds and in those of Congress and the executive branch.
Cautionary note: we are not predicting a strike, but a large number of public comments combined with the seeming acceleration of their number, can be an accurate indicator of military action.