There are also messages saying that is a bogus message...so I am not sure....
PersianKiwi also has Sea of Green will continue on Friday - time and location will be confirmed 1 hour before
From all this I'm guessing that the rebels will do their rally elsewhere from Khamenei's address, to show rejection of Khamenei's authority. Mousavi and the rebels know they will be "disappeared" if this quiets down. Like Julius Caesar, Mousavi has crossed the Rubicon, and knows it's now win or die.