Yes, plasma's can be used, but you have to worry about "burn in" so i'd be sure to get one that has that "shift feature" (sorry dont know what its called)
It shifts the picture a few centimeters every few seconds to prevent an image from burning into the screen.
The shift is so minute, you dont notice.
Honestly, using a plasma for pc use is probably a good question to ask in the audio/video/home theater forum since you'll get way better info and suggestions there.
I can tell you that be sure to get one that does 1080p, not 1080i or 720p since those resolutions will look horrible as a monitor for reading text, and you'll have trouble getting your desktop centered due to overscan etc..etc...
I tried hooking a pc to a 720p/1080i Plasma a few years back and believe me , you'll HATE the results, so stick to 1080p only for using as a pc monitor.