The following BBS article describes the work of Google to analyze malicious and dangerous Web sites.

"One in 10 web pages scrutinised by search giant Google contained malicious code that could infect a user's PC."

Reported via /.
http://it.slashdot.org/it/07/05/11/1628247.shtml
too, using the title Google to be Our Web-Based Anti-Virus Protector?

This is not that new and it's live since last year.

http://www.google.com/search?q=crack%2C+serial++norton