It's official. E! Online is reporting that actress Scarlett Johansson is officially joining Iron Man 2.

Her rep confirms that the actress has signed on to play Black Widow in the Iron Man sequel opposite Robert Downey Jr. The deal was signed this afternoon.

"Scarlett is thrilled to be a part of Iron Man," her rep, Marcel Pariseau, tells me.

Meanwhile, after months of negotiations...

Scheduled for a May 2010 release, part two of the franchise will also include Gwyneth Paltrow returning as Pepper Potts along with Samuel L. Jackson as Nick Fury and Don Cheadle playing Col. James "Rhodey" Rhodes.