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.
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.