I have a Mac running Apache (Default Zend Server Setup) and a AptanaCloud Site (*NIX virtual host).
I thought all Unix based systems were case sensitive, however my Mac doesn't seam to mind on PHP includes but Aptana does. This is quite bore as I when I move my projects from the local server to remote they often don't work because of folder names.
I use the Zend_Autoloader to load my external PHP classes which uses the pattern Folder/Folder/Class.php for Folder_Folder_Class... However there are some custom paths like a folder called models takes classes mapped as Model_. So sometimes the folder has to be lower case and sometimes upper depending on whether it is registered in the Autoloader.