The default filesystem is case-insensitive. Yeah, unlike all boxes in the Unix world. So, there's a few CPAN modules that blow up for that.

Can you elaborate, and finger a few of those suckers?

Windows is case insensitive too, so the same modules will blow up on Windows too. That may or may not matter, depending on how Unix-centric those modules are.

Together with Mac-OSX, that makes a large part of the Perl community. I think that is not acceptable, but maybe that's just me...

I think depending on the case of a file name to distinguish between two files, is a bad practice. Especially for Perl modules. Again, maybe that's just me...