All the theories put out probably have a 99% chance of being wrong, even the cool 3 biblical monsters one. This is no different, and it's not all mine. Others have posted whale angles, but I've been fond of it and spent some time playing with it, so I want to put my version of it here. I invite reasons why it's a stupid idea, but the journey is half the fun anyway. As they say, "It's so crazy, it just might work!"
I've heard a working name for the monster is 'parasite'. So, think of the parasite from The Thing, which is a great monster movie. Think about what it did to the dog and others. The Thing parasite comes from space, and is 'discovered' by Norwegians who dug up a frozen spaceship. Some have said there's an alien angle, so that covers that. At the end of the Thing, everyone is doomed, and Carpenter even called it the first of his Apocalypse movies.
However, there is no proof the parasite is destroyed, and is free to be frozen again in the Antarctic, to be found again for a new movie. A slusho is frozen ice, as antartica is. The slusho history says the ingredient must be kept cold. If a new team found the alien parasite from the Thing, they would be wise to keep it cold.
So a team could find the parasite, or maybe just the spaceship with some of the parasite still in it, and bring it back to a NYC museum for research. In NYC there is a 94 foot blue whale on display. Yes, it's a model, but maybe they say part of it is from a whale, with it's dna. It is the world's largest replica of a creature, not a bad target to bring to life.
If the parasite got ahold of a whale, it could make one mean, weirded out monster with spider legs, tentacles, who knows what. And of course a huge mouth for spitting out the Statue of Liberty head.
As we all know, the slusho site tells the story of how an ingredient turned Ganu into a big whale in his dream. Also, I still think the phrase "....it's alive..." is a big clue. You might say that if you saw something that you knew wasn't supposed to be alive, but now is, like a museum whale. The slusho site also has the blue-oven-mitt thing, which many have connected to Orka/Whale. I've heard audio comparisons that people have done showing the blue whale sound very similar to the cloverfield 'roar'. What would the sound be from a 400 foot super-whale?
[added8-29: Now there's a new youtube video comparing the sound of the cloverfield roar to a roar in The Thing. http://www.youtube.com/watch?v=nhUrKZtav4A ]
Here's an artists concept using a whale as the cloverfield monster.
In the Thing, the alien ship is found by Norwegians, and the slusho site plus Rob have japan connections. I know, it's goofy, goofy, but I think back again to the band from Switzerland (swiss cheese anyone?) called The Monsters, who have a label on their photo saying "100% Whale Approved - Japan and Norway". http://www.themonsters.ch/Gifs/knoedel1.jpg I thought nothing of that weird connection, but then read that jj used real existing sites for his games, like the Jeep site. What if he paid that punk group to add the label on top of their photo, and allow a password to activate their form? I don't see anything else in their history or material that references whales, so that label sticks out.
In the end of the Thing all the heroes die (9 I think). I've heard the cloverfield movie is all a flashback, so maybe they are all doomed there as well. Even if the army were called out to blast the 'monster', if it had the parasite in it, it would just infect people all around, creating a situation hard to contain. Lots of smaller land-whales?
After reading all this, I realize how insane this sounds. I hope I don't annoy anyone, but it's summer break and I have nothing better to do.
JJ put a polar bear in the Lost island, why not whales in Manhattan? Or maybe I'm still stuck in my review of Whales on Stilts.