You don't mention which model you are interested in. Here is a link to someone measuring the power requirements of a 42pwd7uy vs a 20" lcd and a 27" crt. This plasma required the equivalent power of about 2 1/2 60Watt light bulbs. Hardly worth worrying about and probably close to the power required by a 32" CRT TV.
http://www.avsforum.com/avs-vb/showt...ts#post5110748
http://www.avsforum.com/avs-vb/showt...ts#post5110748