autofs refuses to mount ntfs-3g filesystems, because mount.ntfs-3g does not understand '-n' mount option passed by automount when /etc/mtab is a symlink to /proc/mounts and refuses to mount a filesystem. mount.ntfs-3g should ignore it and pass. Patch follows, ntfs-3g guys told they will put it to use in next release :-)
Created attachment 248462 [details, diff] src patch, to $FILESDIR
Created attachment 248463 [details, diff] ebuild patch
This is fixed in sys-fs/ntfs3g-2010.10.2 which is now in the CVS tree.