To confirm this behaviour is still current:

Python 3.3.0a1+ (default:958a98bf924e+, May 21 2012, 22:18:16)
[GCC 4.5.2] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import ntpath
>>> ntpath.normcase(r"c:\mixedCASE")
'c:\\mixedcase'

In general, I'm not so sure of the use case of the function /at all/ - possibly something like
  
if normcase(path1) == normcase(path2):
    ...

however, this can give the false impression that two files are the same - I think, given a Samba share with two files 'A' and 'a', it's possible to access both files from windows.