Thats a new one

[Linkster]

From what Ive seen every one of the sites that had that warning - and yes its been around a few months - has actually had a hacked script put on their pages (on the server) by someone else, or is intentionally doing it. In most of the cases it was a hacker that had gained access to a tgps server and installed the trojan script - then allowed it to copy itself to every page it could find.
I also noticed that Google is very quick about removing the notice as soon as its fixed so they must do some kind of re-botting for those sites it lists that way