No surprises in terms of who they are, but their statement is noteworthy nonetheless in terms of making a point: The internal PRD factions (technically termed corrientes de opinión) Nueva Izquierda, Foro Nuevo Sol, Alternativa Democrática Nacional, Izquierda Renovadora en Movimiento, and Unidad y Renovación, formed a coalition called "Demócratas en Movimiento" to back Marcelo Ebrard for the 2012 PRD candidacy.
All, with the partial exception of UNYR, belong to the social democratic or democratic socialist factions of the PRD, and their backing of Ebrard has hardly been a secret (UNYR was formerly a very pro-cardenista faction and at times appeared quite "radical," yet is now largely centered around the Transportation secretary of Mexico City, Armando Quintero).
The earlier spats between Ebrard and particularly Nueva Izquierda in 2007-09 to me always appeared pointless - e.g. Ebrard backed AMLO's candidate for the party presidency in 2008, even though he was much closer ideologically and programatically to these social-democratic and socially liberal factions. Ebrard and NI were always natural allies, and Ebrard did not distance itself from the new group, but naturally embraced it, as he should - AMLO, lest we forget, have a 5-year head start on Ebrard, having built his new movement since 2006.
What is important is that all these five factions - NI and ADN by far the largest of them - together have an absolute majority within the PRD, including on its national council, should the PRD decide to determine its 2012 candidate through a vote there.