Hi
Ive owned a old Panasonic plasma for 3 years before i changed it to a new version, i use my Xbox 360 and PS3 pretty much every day and have never had a problem with plasma screens with burn issues even when i owned my old plasma to now using it on my new plasma.
I would suggest one thing though, if you use your games console/s on your plasma to make sure the picture is set on normal, not dynamic or high brightness etc as this could cause burning on your screen, aslong as you set the picture up correctly, then you wont have any problems, might be a good idea to set it up using the THX optimizer as this calibration does not use very high levels of brightness etc.
Regards> M