I am making a video program for my school that is going to be looped on a large plasma in the office for potential students. It is basically student work with titles over top. Some of the video is anamorphic, some is fullscreen, some is HD. I am going to put the whole thing into 4:3 so there are going to be letterbox bars for alot of the video, and they want a school logo in a bottom corner for the duration. Now for my question...

Unless I do this right, it is most likely going to burn bars and the logo into the plasma. I have heard that using grey letterbox will prevent it, as well as using a semi-transparent logo. Has anybody done this or had problems with plasma screens burning?

Yep, both bars and logos will burn marks into your expensive display - plasma is slowly dying, by the way, looks like it's no more main stream, at least not for consumer product.

Gray bars instead of black and reduced luma on the logo will not prevent, just slow down the burn. Some advanced plasmas have a function where, when 4x3 material is sensed, it's slowly moved on the screen, so it won't burn - you can do that yourself in editing. Let's say you have a three minutes 4x3 segment - keyframe it, pan it left, then slowly move it so by the end it reaches the right side. As for the logo, try to convince them to give up.

(I assumed the plasma is 16x9).

If plasma is going away it's a shame cause I still feel that when viewed side by side a plasma still looks better than an LCD. Something in the image is just... crisper. I'm sure that's not the technical term for it, but even with the newer LCDs on the market I find plasmas more pleasing to the eye.

Further to what Ervin says, is it possible to animate the "static" logo to move across the screen or disappear and reappear in different locations and still look good? Rather than a network style "bug", can you make the logo and integral part of the style of the video segments and move it around accordingly?

I second the idea of moving the logo around. If instead of just solid colored bars what about using animated motion, something like Digital Juice backdrops. This would add a little pizzaz to the work and keep things moving. Doesn't ESPN HD use something like that when they display 4:3 material? Or perhaps changing the color of the bars, maybe incorporating the school colors and have the bars switch colors every so often.