Given that it's an identity that 600 million people around the world already use, the push by Facebook into the publisher comment space is undoubtedly going to be a very, very strong one. And the fact that Yahoo is on board with the launch magnifies that strength. But it could have been even stronger. Facebook originally planned to use Twitter and Google logins for the commenting system as well. But both were scrapped in the final hours leading up to launch for unspecified reasons, according to people familiar with the matter. Actually, to those who have watched the space over the past several months, it's pretty clear why the options vanished: all the players involved just plain don't like each other .