In late November 2007, hackers loaded more than 40,000 infected Web pages and thousands of search terms, then used botnets to elevate their search status. This led search results to list the poisoned pages high and even first in some cases. The iinfected sites contained no useful information, however, a click on a link would launch an attack. Although the attack was nefarious, experts still vouch for the safety of search engines--as long as your software is patched and up to date.
Read the full story on Yahoo News: Hackers rig Google to deliver malware.