Man - not sure why this didn't grab the media's attention until today: http://www.pcworld.com/businesscenter/article/147503/group_says_google_a_top_source_of_badware.html

March was apparently a bad month for the Google properties: http://blogs.stopbadware.org/articles/2008/04/05/infections-stats-for-march-2008 (wasn't this also around the time the bad guys figured out they could XSS various high profile web sites that were accepting tainted search result data from Google without sanitizing it?)

Google's response: http://blogs.stopbadware.org/articles/2008/04/07/commentary-on-top-infection-stats

Also of note is the Badware.org response to Naraine's blog calling Apple to task for distributing potentially un-wanted products with Safari security updates: http://blogs.stopbadware.org/articles/2008/06/24/naraine-apple-software-update-still-badware