Further depressing news is that according to 'Dark Reading' (Sep 09), Zeus is very successful at eluding detection even with up-to-date AV. They quote 44% of Zeus-infected machines running no or out-of-date AV but the other 56% fully up to speed. Their opening paragraph:
The most pervasive banking Trojan evades detection by antivirus software most of the time, according to new research.
It would appear that the Mac is equally vulnerable, don't know about Linux.
Deep joy!