by IdiotProof:
Funny how everybody credits Google for NTFS read-write support on Mac OS.
The reality is that Google just ported Linux FUSE (the ability to write filesystems in userland) to Mac OS. One FUSE module implements NTFS by glueing the FUSE API to the libntfs-3g API.
But make no mistake, the real work is done by libntfs-3g, whose authors should be credited instead. See
http://www.ntfs-3g.org/about.html for details.
Parallels also has the ability to modify an NTFS filesystem from their main binary (i.e. without using MacFUSE). They use it to modify an NTFS Boot Camp volume before booting it in a virtual machine. I wonder what code they use to achieve that.