Looks like Microsoft took the Blaster and Sobig viruses personal. As of November 5th, they are now offering $500,000 in information rewards.
They are asking if you have any information that can lead to the arrest of the virus authors, to give it to law enforcement.
More information can be found at:
http://www.microsoft.com/presspass/press/2003/nov03/11-05AntiVirusRewardsPR.asp
and
http://www.microsoft.com/security/antivirus/