After launching the Relevant updates for Lion and Snow Leopard, Apple does the same with Leopard and has published a new version of the system that, among other novelties, incorporates the necessary tool to automatically remove any trace of the Flashback Trojan and its variants.
If the system detects that your Mac is infected, you will be conveniently informed and a dialog box will inform you that the malware has been removed. Another security measure that this update implements is the deactivation of the Java plugin for Safari.
In some cases, after downloading and installing the update, it may be necessary to Restart your computer for the tool to start working properly.
As always, you can download the update for Leopard at Software Update tool included as standard in OS X.
More information - Apple launches utility to detect and remove Flashback Trojan
Source - 9to5Mac