Dread Central claim to have an inside source on the "Cloverfield/1-18-08" project who has talked a bit about the monster we can expect to see:

"It's not Godzilla or Voltron (duh) or even Cthulu; anyone expecting there to be some sort of elaborately detailed backstory may be in for a disappointment.

Expect an old-fashioned monster movie retold in a very modern Blair Witch sort of way - but with a twist. You see that giant monster that emerges from the ocean to begin laying waste to New York City ... it didn't come alone.

Much of the movie will revolve around the characters fleeing for their lives, not from the big one stomping the city, but from the "raptor-like" smaller versions hunting them down.

Word from the start has been that this would not be a mega-budget movie and the digital effects work needed for a giant monster trashing New York City would no doubt cost a heck of a lot more than street level action of people being chased by smaller monsters."