I've had LOTS of WN nappies over the years, got her first at 3months and she still has it now.
Even though Scarlett has potty trained i still have *counts* 9 WNs
At one point i used to have one on order continually, get one, order one... wait for it to be delivered, order one - you get the idea lol. Then eventually i found i had/had owned most of the embroideries/fabrics i wanted etc and dwindled off, right about the time my fitteds addiction then took hold
Im not sure if i would say theyre the 'standard' yet, im sure if you asked a none cloth board user what a Tots Bots or BumGenius was they would know, but i dont think they would know what a WeeNotions was, purely down to advertising and magazine coverage etc.