Actually, the Wand of Nothing, like many other wands (see http://www.steelypips.org/nethack/wan1-331.html), has 15 charges. However, as with any other wand, when it is empty, it will display the message "Nothing happens" unless a 1/127 chance comes up, in which case the last charge is wrested and the wand is destroyed. This explains why one can indeed zap a Wand of Nothing several hundred times. | 
