Snow Leopard, the upgrade for the Mac OS X (Leopard) has been released last week. Did you buy the upgrade already?
Well if you do then you might want to check the version of your Flash Player. It has been reported by PC World that Snow Leopard downgrades your Adobe Flash Player to an older and less secure version (from 10.0.32.18 to 10.0.23.1).
To check your version, you can visit this version test site from Adobe. Or you can also navigate to the Installed Plug-ins section on your Safari.
The official updated version of the Adobe Flash Player can be found here.
Even though not much virus is introduced in the Mac system, hackers can target third-party plug-ins such as the Flash Player to deposit malicious codes.