Ok, here's my nickel's worth on the whole thing.
Nope. The cube is just a cube. There's no bodies in it, there's nothing special about it other than the painted hearts. Glados knows this, and she's playing the old double reverse psychology game on you. We've come to assume that everything she says is a lie, or should be taken with a dumptruck's worth of salt. So, at this point, she tells you the truth about the cube, knowing you'll expect her to be lying. Thus, when it comes time to destroy the cube, you're hesitant because you think there's something more to it because Glados said there wasn't. Then, she gets the added bonus of guilt tripping you about destroying a pointless item. This is compounded when she says you destroyed it faster than anyone else, even if you hung around for like fifteen minutes looking for another option.
So, that's the game. Here's the comic: Ratman was NUTS. It was his own mind talking to him. The reason the pill bottle was mislabeled is to avoid getting sued for using the actual name of the medicine. In a non-meta explanation, maybe it was Aperture's own version of the stuff. Glados' manipulations just plain worked on him, to the point that he DID bond with the cube. As to his wall o' crazy with all the pictures, maybe he'd been alone and at the mercy of Glados so long, the only way he could recognize something as relatable was to put the cube over it.
Some else pointed out the vaporized cube in 2, so I don't have to go there. Gracias.
Regarding Glados' comments about the cube in 2, we're looping back around to my first point. Glados is still playing with your head, in the exact same way. Also, here's the meta version: the developers never expected the cube to get so much traction in the first game, or the fact that players got attached once they renamed it a Companion Cube. This time, they were having fun messing with the cubists by destroying a mess of 'em right there, and telling the player they were worthless.
...yep, I think that's everything.
