Have you checked you Mac for the Flashback Trojan already?
The Flashback Trojan infected 670,000 computers worldwide, 98% of them running Apple's Mac OS X. It appears that the number of infected computers is down to 270,000 (PC Mag, quoting Symantec).
Apple is still coming out with a removal tool, but there is no need to wait for that. If you still have not checked your Mac I recommend you:
1. Download and run the Kaspersky Flashfake Removal Tool.
2. If you are running Mac OS X 10.6 (Snow Leopard or later) the software update on your Mac and install the Java and other updates. If you are running Mac OS X 10.5, there is apparently no patch on the way so I would recommend disabling Java on your Mac.
3. Consider install an Anti-Virus program like Sophos Free AntiVirus for Mac.
Do you part in bringing down the number of infected computers to 0.
Update: The official Apple Flashback Removal Tool is now available. Just update your Max OS X 10.6 or 10.7 and that is that.