Berry and Jackson's casting in the Broadway production of the Olivier Award-nominated play has been rumored for months. Berry made the announcement during the premiere of her new film "Frankie and Alice." No official casting has been announced.

The New York Post first alluded to the casting of the two Hollywood heavyweights in July. Jackson has participated in previous readings of the play for industry members.

The Mountaintop is aiming for a fall 2011 Broadway arrival. Sonia Friedman (La Bete, La Cage aux Folles) and Jean Doumanian Productions will present the play that will be directed by Kenny Leon (Fences, A Raisin in the Sun).

The Mountaintop premiered at London's Theatre 503 in June 2009. The play transferred to the Trafalgar Studio 1 in the West End and earned the Olivier Award for Best Play. David Harewood and Lorraine Burroughs starred.

Here's how producers describe the work: "Taking place on April 3, 1968, The Mountaintop is a gripping reimagining of events the night before the assassination of civil rights leader Martin Luther King, Jr., as he retires to Room 306 in the now famous Lorraine Motel in Memphis, after delivering his legendary 'I've Been to the Mountaintop' speech to a massive church congregation. When room-service is delivered by a young woman, whose identity we puzzle over, King is forced to confront his past, as well as his legacy to his people."