Anonymous already announced that it was not the groups intend at all to attack facebook, the social media they use the most to keep in contact with other members, but it was only one of their members threatening to do it.
Wasn't it supposed to happen on November 5th if they were trying to do it? And like the person above said, they said that they were not going to do it.
This attack was never legit. It was just some member trying to act for the whole organization. What was actually happen on this day was that they were going to release information about the Mexican Cartel called "Los Zetas" which is translated to "The Z's". But I think they also got their member back, so everything was okay I think.