OK, so at some point yesterday Blue Security caused TypePad/Six Apart to be DDoS'd. Also, as a result of Tucows Managed DNS service hosting bluesecurity.com's DNS, they caused (at least indirectly, this time from what I can tell) Tucows to be DDoS'd yesterday afternoon.
A few hours ago, UltraDNS was their DNS provider. Now, it is Prolexic which reportedly uses UltraDNS for their DNS services. Who's next?