I'm almost sure that someone already mentioned this, but, just in case...
Should be good for marketing: there is a very fundamental difference between 51% attacks in PoS and PoW. In PoW, if somebody controls 51% of hashing power, he call kill not only, say, BTC, but also all of its clones that rely on the same kind of algorithm, with no additional cost. In PoS, however, after spending a lot of money to get a sufficient stake and killing a coin, the bad guy would have to spend more and more money to kill the clones that the community may start after.
Nice. To the moon.
