Update: MichaelBay.com has posted the trailer along with links to download the 720p & 1080p HD versions of the trailer.
Update 2: Hit the links below for lots of screenshots from the trailer with number of pics in parenthesis.
Official Synopsis:
When a mysterious event from Earth’s past erupts into the present day it threatens to bring a war to Earth so big that the Transformers alone will not be able to save us. The movie stars Shia LaBeouf, John Turturro, Josh Duhamel, Tyrese Gibson, Rosie Huntington-Whiteley, Patrick Dempsey, Kevin Dunn, with John Malkovich and Frances McDormand.