July 18, 2007 - DreamWorks Animation announced they've set Monsters vs. Aliens to be released in theaters on May 15, 2009. The new date is earlier than had been previously announced and moves Monsters vs. Aliens into theaters a week before James Cameron's Avatar is set to open.
According to DreamWorks Monsters vs. Aliens is a new take on the monster movies from the 1950s. The film, which is described as an action comedy, will be produced using stereoscopic 3D technology.
Conrad Vernon (Shrek 2) and Rob Letterman (Shark Tale) are directing the film with Lisa Stewart producing.
Source: DreamWorks Animation

