Helpful Links Regarding Flashback Trojan
A link to a great User Tip about the trojan: Flashback Trojan User Tip
A related link in the tip to a checker: Malware Checker Dowload Link
A Google search can reveal a variety of alternatives on how the remove the trojan should your computer get infected. This can get you started.
For now I recommend the User Tip from etressoft to detect and remove:
Kaspersky Flashback Trojan Site:Flashback Trojan Detection and Removal
Also see Apple's article About Flashback malware.
Go to F_Secure's Flashback Removal Tool web page, download their Flashback trojan detection/removal tool, and follow the instructions you find there. In my opinion this is currently the most complete and reliable tool available.