SEO : Search Engine Optimization.
No, it's not another buzz word. It's a technique used by malware authors to propagate their malware. They use one of the most respected search engines today (Google) to make their way into the user's machine. Piggybacking on a prestigious, and highly trusted search engine is an efficient and effective way to reach out to billions of users worldwide.
Rogue AVs usually use this method. They create fraudulent sites (site A) which redirects to another site (site B) which in turn downloads Rogue AVs into the system. The malware industry makes sure that Site A gets a hit during Google search by targeting search queries that are sensational or new, for example, the Haiti earthquake.
In light of this, users are advised to be vigilant when accessing sites. When even Google is used as a medium by malwares, blind trust on returned links is unacceptable.