Yes they can. I think the accepted maximum is around twelve faulty pixels. However, don't worry too much, like TFT, plasma panel production is much better now and I've only ever seen one Plasma screen with one dead pixel, so providing you don't buy a B grade stock item, you should get a flawless display.
A bit like the days of early Shadowmask CRT's circa 1968. You often used to see small black splodges where some holes of the masks were blocked up in the production process but almost never now.
Spasm, the accepted maximum pixels is dependant on the manufacturer but 12 sounds about right as a guideline. To put your mind at ease a little we haven't had one customer complain of stuck/dead pixels, ever! As Norman says, the manufacturing process is much more efficient now than it was on the early gen screens. HTH
Thanks also Liam for your answer to Spasm. Apols that this is off thread but from this forum, there seems to have been a few problems with buzzing Plasmas. Have you had much trouble in this area?
Take a look at this thread from the avs forum http://www.avsforum.com/avs-vb/showthread.php?s=&threadid=182068&pagenumber=2 The user Techniwizard works for panasonic and gives a good explanation of the fact that they all buzz. John.