Today my parents came across an OS X trojan of some sort, while surfing the Internet with Safari. It’s called “Apple Security Center”, and by the sound of things, it tries to trick users into downloading a fake anti-virus program, like the recent MAC Defender. After a bit of Googling, I couldn’t find much more than this forum thread on the official Apple forums. This post in particular contains a screenshot of the webpage (also pictured below) and notes that the website IP address is 184.108.40.206. For reference, the website IP address that my parents were directed to was 220.127.116.11.
If you happen to have downloaded it, removal instructions are contained in the aforementioned thread on the Apple forums.