The Pan Pacific Defense Corps is testing their alert system... and leaking some information. Updated 11-30-12
Source: Blueprint: How to Build a Kaiju-Fighting Giant Robot
The Pan Pacific Defense Corps have started testing their new system to alert the affected area of impending kaiju attacks. Remember, this is only a test.
The Pan Pacific Defense Corps also have a countdown (~ 2 weeks at last check) on their website, counting down to something.
These are, of course, promotions for the upcoming film, Pacific Rim; a story about giant robots (Jaegers) versus kaiju (Japanese term for strange beasts, nowadays often referring to giant monsters). These "viral" promotions were made extra authentic by the leaking of classified materials (what agency does this not happen to?) on a number of different websites.
Pan Pacific Defense Corps Jaeger Initiative nomination document
Jaeger Gipsy Danger blueprint
Pacific Rim, directed by Guillermo del Toro, hits theaters on July 12, 2013.
The first trailer for the film is expected to be attached to The Hobbit: An Unexpected Journey film on December 14, 2012 (around two weeks from now).
UPDATE: Looks like San Francisco has fallen victim to kaiju.
UPDATE 2: Two more Jaeger blueprints were revealed today (11-29-12)
Russian-named Jaeger Blueprint
Coyote Tango Jaeger blueprint
And yet another blueprint...
Striker Eureka Jaeger blueprint
And another, now from Hong Kong (11-30-12)
Crimson Typhoon Jaeger blueprint