Although unconfirmed at the moment, Newsinfilm.com is reporting what it claims is the plot synopsis for Pacific Rim. This does seem to fit in line with previous rumors, however, that this was at one time being looked at to be modified as a new Godzilla movie. Guillermo Del Toro will be directing this film starting in September for a release in 2013. There are potential spoilers below, so if you don't want to know anything about the setup for the film, stop reading here:
"In alternate version of Earth in the near future, decades after a historic date in November 2012 when the first kaiju, a towering Godzilla-like beast, emerged from a hole in the Pacific Ocean and attacked the city of Osaka, Japan. The second is 'The Anteverse,' another universe on the other side of that gaping portal, 5 miles below our ocean’s surface.
Since the first attack, the rim has been 'spitting out' a variety of gigantic monsters at an increasing rate, which then stride out of the ocean and begin destroying sea-bordering cities, like Tokyo and Los Angeles. In order to combat these monstrous, otherworldly menaces, the military developed the 'Jaeger' program, which trains teams of two pilots to jointly operate massive, building-sized mechanized suits of armor and high-tech weaponry."
For more information on the plot, check out the source link below. Also, remember that while this is considered to be the plot synopsis, it has not officially been confirmed, so details may change. Between this and the upcoming Godzilla movie from Legendary Pictures, we should have a good couple years of monster movies. [Thanks /film]