In the license file that comes with the WDK, section 2a I, second bullet
point.
You may modify, copy, and distribute the source and object code form of code
listed in the SAMPLES.TXT file. You may modify, copy, and distribute only
the object code form of other sample code that is not listed in the
SAMPLES.TXT file.
The fastfat driver is not listed in the SAMPLES.TXT file, so that seems to
imply we cannot redistribute the source. Unless you're suggesting we don't
care about not being able to distribute code we include with ReactOS?