The Dutch police have arrested three men, ages 19, 22 and 27 year-old, who were running a network of compromised machines that was counting around 100000 total.
The 19 year-old is considered the prime suspect and the coder of the virus used, W32.Toxbot. The virus was first noticed at the start of this year.
An IRC channel was used to control the bots, and send them commands. They were used in DDoS attacks, and information was collected from online banking services (PayPal) and eBay accounts with the aid of a key-logger.
The group is thought of to be responsible for at least 1 extortion attempt of a company which is located in the US.
At the time of arresting the suspects, the police confiscated computers, administration, a bank account, cash money and a sportscar.
21 Oct 2005 Update: As Dutch media now reports, the number of infectees was not around 100,000, but rather 1,500,000 machines.