The people at Typepad understood that many of us really wanted a report or more explanation for what happened last week when service collapsed for several days. They've offered that explanation here. It strikes me as an honest account that is more than thorough enough. They covered both the technical side of the attacks and their ultimately successful efforts to thwart the evil-doers.
They indicated that the authorities are involved, so they're limited on some things they can say, but that's entirely understandable. They didn't mention anything about extortion, but given that this has been an m.o. in recent, aggressive denial of service attacks, it seems a reasonable assumption of motive for the sophisticated, sustained attacks that took Typepad down.