Microsoft's DCU and some federal agencies took down the Rustock botnet two days ago. A hearty CAUCE congratulations to all those involved, in the forefront, and behind the scenes.
Here's a compilation of various news and data sources:
Krebs on Security: http://krebsonsecurity.com/2011/03/rustock-botnet-flatlined-spam-volumes-plummet/
Wall Street Journal: http://online.wsj.com/article/SB10001424052748703328404576207173861008758.html
Microsoft: http://blogs.technet.com/b/mmpc/archive/2011/03/18/operation-b107-rustock-botnet-takedown.aspx & http://blogs.technet.com/b/microsoft_on_the_issues/archive/2011/03/18/taking-down-botnets-microsoft-and-the-rustock-botnet.aspx
CBL (2nd & 3rd charts) http://cbl.abuseat.org/totalflow.html & http://cbl.abuseat.org/rustock.html
Spamcop: http://www.spamcop.net/spamgraph.shtml?spamweek
Nixspam: http://img.ly/3eix
The court orders (PDF) http://bit.ly/fg0d0u