[eluser]coolfactor[/eluser]
Windows and Mac file systems are not case-sensitive by default, but Linux is. CodeIgniter documentation says to keep the first letter uppercased, but lowercase the rest of the letters. This is only important for the file name. Internally, the name of your class can be whatever you want.
I don't like CI's naming conventions, but I've learned to adapt. It's the only way to ensure operability between file systems.