My favourite bit of Mac-zealotry has come with the revelation that people who use iTunes shouldn't upgrade to Windows Vista because of compatibility issues. I've read the views of several Mac-zealots decrying this is yet another problem caused by Microsoft, when it is really down to laziness on the part of Apple.

If you can say "my product is not compatible with this operating system which has been made available for developers for around a year" and have people point the blame at the developers of the operating system, you've got a dangerously loyal customer base.