Mac vulnerability may also affect Windows

At the CanSecWest security conference a New York hacker has successfully developed a zero day exploit for a vulnerability in Mac OS X which can hand over control of a computer to a remote attacker. It turned out that the vulnerability is in the interaction between QuickTime and Java. Attackers will now more likely try very hard to replicate Dino Dai Zovi's work, and they'll be looking very closely at QuickTime and Java, especially on Windows.

The best precaution is to disable Java in whichever browser you favor until there is a fix from Apple. If you need to use a web site that requires Java, decide whether you trust the site before turning it back on, and don't forget to disable it again when you've finished.