I just stuck a 1TB drive in my PC a couple days ago, but that's overkill for current consoles. There's no point in storing anything but games and DLC on the console itself - you serve movies and music and stuff to the console via some PC media server. If MS had something like Play TV for the 360, maybe there'd be a point to a drive that big in a 360. Heck, I don't expect to fill up my 1TB drive for a while, and I'm getting an HD camcorder for my birthday.
The next generation of console might come with a 1TB drive, but not this gen.