Only if you run it through some specialized video equipment/software can you gain this effect. It wouldn't be built in any consumer plasma or LED/LCD I have seen of late.
I have been looking at new HDTV's and was curious is there a way to split the screen 2-4 ways to have multiple inputs on the same screen?
Hypothetically a 4 HDMI slot TV with xbox and television going at the same time? I am not looking for picture-in-picture as one of the inputs would be significantly smaller than the other.
Any help would be extremely appreciated.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic