The story starts with a couple of articles in the Washington Post (here and here)

Spammers have moved to botnets to generate huge volumes of spam but they still depend on Internet infrastructure. In this case, security experts where able to find a single point of failure in the spam system,

a major U.S. hosting service for international firms and syndicates that are involved in everything from the remote management of millions of compromised computers to the sale of counterfeit pharmaceuticals and designer goods, fake security products and child pornography

Take out the choke point in a system and you shut down the system. Resilient system design avoids single points of failure like this. Spammers, bot herders and malware developers have proven to be quite able to adapt to emerging threats and opportunities in their domain. Simple strategies like redundancy can go a long way to improve resiliency; more complex models like peer-to-peer computing, like that already used in botnets, may be extended to reduce single points of failure.

We can have some relief from spam for now it will be back and when it comes back it won't be so dependent on a single provider. Whatever the new infrastructure is, it will be more difficult to take down.