A UK site got infected by a malware. A couple days later, its ranking were gone. Traffic down 70%.
Mid October, a UK site got infected by a malware. The malware spread though the ad serving system to different page types. The development team cleaned up the malware and patched the system in a day. After having cleaned up the site from the malware, I requested a malware review from the webmaster tools console.
Google resources:
www.google.com/support/webmasters/bin/answer.py?answer=163634
www.google.com/support/webmasters/bin/answer.py?answer=163633
My name is Hervé.