Earlier quoted context omitted.
This attack is scheduled to come soon after anon switches from LOIC to a "new cannon" dubbed #RefRef ( http://anonops.blogspot.com/2011/08/new-hacking-tools-by-ano... ). They're probably way overconfident in their abilities (#RefRef's description is thoroughly unconvincing), but at least they don't think they're going to DDoS one of the best-prepared sites in the world, AFTER telling them exactly what day the attack…
So if we assume these people have any idea what they're talking about, it's some kind of SQLi attack... presumably mySQL? I wonder at what point it'll occur to them that Facebook mostly serves data from memcached. Uh... did I get something wrong here? A correction or something would be nice.
if this is in fact anonymous. i'm not convinced, too big a target for them to have so little fanfare/flair.