[Deprecated] CocoaJava: com.apple.cocoa.foundation.NSRuntime
-[NSJavaVirtualMachine initWithClassPath:] FATAL: cannot initialize ObjCJava. Exit
So, it appears that ClamXav 1.x will not run on Snow Leopard. Upgrading to ClamXav 2.0 beta fixes this. The new 2.0 interface also allows for version checking and will automatically guide you to update your clamav scanning engine quite painlessly.