Apparently Google now checks web sites for safety, sifting out harmful code to browsers and posting a warning on the Google listing that the site has safety concerns. http://news.bbc.co.uk/1/hi/technology/5251742.stm
http://news.bbc.co.uk/2/hi/technology/5251742.stm This is good coming from Google. But if Google know which sites are unsafe why don't they ban them outright?
The pop up message will be something like: "Congratulations! You just got a Trojan on your computer!" and some sponsored links on the anti-spyware soft!