I just got into an email discussion with someone on this topic. She's on a Mac. Her website was hacked. We speculated as to how that could have happened since Apple keeps insisting that there's little risk of viruses or trojans on Apple machines.
My speculation?
She may have used open wifi access points to access ftp or her admin area of her website and the un/pw may have been snarked off the connection.
So maybe we also need to open up the discussion to that aspect. I know that there are anonymizers for windows and linux machines, which will encrypt two way traffic when using open networks. Anyone else have any ideas?
I also suggested she might have a less than optimal sysadmin at her hosting.
Slashdot has been reporting an uptick in Mac Worms and security vulnerabilities, so maybe with the advent of Vista (resulting in larger popularity for Mac!) it's possible that destructive hackers may turn their sights on Macs now, as well as Windows.