When the tv is off, they could be tilted at 45 degree angles, and when one is on, it is at the normal horizontal position...
Curious - what is the point of tilting the TVs? Horizontally or vertically?
For this, I know I need 2 big servos and a way to detect if the tv is on or off...
I would personally tap directly into the power supply of the TV, and see if I could find a 3.3 VDC or 5VDC output that is only on when the TV is on (or maybe find a digital signal somewhere on the TV for the same). It would void any warranty on the TVs, though. You might also try to detect the backlight of the TV in some manner.
Lastly - presuming you get to the point of actually doing this, why do you need that much TV? I have a 42" LCD sitting on my wall that rarely gets turned on (the occasional DVD movie is about it); one of the best things I and my wife ever did was to drop cable TV. There's very little on it that is worthwhile, and anything you generally do want to watch can be found online in some format, or thru other "channels".
Now - if you are intending this to be for some form of "ultimate computer display system" (aka - like a mega/giga-pixel display wall, or some kind of multi-head simulator surround system) - that may be used for watching the occasional bit of entertainment; sign me up! I love my dual-head system I have on my desk (dual 22" 1680x1050 LCDs right now); a system like you're proposing would be heaven, if I had the desk room (which I don't, unfortunately)...
