Yesterday, Robert Downey Jr.teased of an Avengers related announcement on Good Morning America today. There were also four teaser images posted by Downey, GMA, Jimmy Kimmel and Marvel. Which made it seem obvious that the announcement would involved GMA and Jimmy Kimmel Live… which it did.
The Avengers will assemble on both shows this month in anticipation of the May 1st release of Avengers: Age of Ultron. They will appear on Jimmy Kimmel Live on April 13th and on Good Morning America on April 24th.