It has been reported a few days ago that the FBI has arrested Oleg Nikolaenko who is believed to be behind the botnet called Mega-D. Early November he was arrested in Las Vegas, and held responsible for managing the botnet which is sending roughly 30% ~ 35% of all spam worldwide. Apparently a large spamming operation called Affking is being tracked and hunted down by the FBI. Doing research the FBI found email traffic between Nikolaenko and an Australian partner called Atkinson discussing spamming operations. They also found the executable file for the Mega-D malware, notes FBI agent Banner:

When the botnet was taken down, Banner says in his complaint that Nikolaenko was in the US but left the country two days early, likely to go home and fix the damage.

The trouble with botnets is that they still survive because of people knowingly or unknowingly download and install malware which runs the botnets: a good firewall plus common sense about what you are downloading could help in bringing down the spam volume sent daily (which sits at no less than a staggering 195 billion emails).