A while back I wrote about a new system Google had, where a warning message would appear in the SERPS if Google thought the site was dangerous, and how easy it was to defraud that system.
Matt Cutts has posted about how webmasters can use the Webmaster Console to track down malware hosted on their site. This is excellent stuff – I like how Google is slowly making it so that webmasters have more and more access to the information Google already knows about their site.