Apparently conficker has a list of 250 different domains that it checks to looks for instructions, not all of which are registered yet. The alliance of companies that has been put together to fight conficker is buying up all of the unregistered ones so that it has fewer places to go fo rinstructions (and presumably getting the registered ones removed?). Once the list of domains is taken out, conficker has to fall back to a p2p method of getting orders which sounds not to be very robust.

http://tech.yahoo.com/news/pcworld/20090213/tc_pcworld/confickerwormdrawsacounterattack