Tried to fill the screen of my video camera with as many screens as I could fit in. Managed to squeeze in 12 screens - an old rear-projection TV, another cathode-ray TV, three computers, an extra monitor connected to a computer, a portable DVD player, an iphone, an ipod video, a mini-TV and two projectors projecting onto screens. Filmed from three cameras. Plus, a few extra DVD players were needed to feed signals.
Our household happened to have a lot more electronics than the average one, but what with the proliferation of new TVs, mobile phones, MP3 players, and digital cameras - I'm sure many North American households have their own fair share of screens.
As to why I selected certain images to be on the screens, I'll leave that to the viewer's imagination ... but I will say more of my energy simply went into setting up the room, and we were in the process of moving out, so there wasn't time to really work develop the images or create the kind of dialogue between the screens that would have been worth exploring.