First of all the links are not a feature of the operating system but rather a feature of the file system (version).
That's not really true. Even though ext2 supports symbolic links, on XP with an ext2 driver, you still don't get symbolic links. So you need the feature *both* in the operating system and the file system.
The fact is valid for Unix as well but most Unix file systems support hard- and soft links anyway.
As do most Unix implementations - but I still remember Unix implementations which didn't support symlinks, not even in the API.
To my best knowledge links are only supported on NTFS. FAT doesn't support links and IIRC it's not possible to create a hard link on a remote file system.
The latter is not really true: NFS most certainly supports hard links. I can't try right now, but I would be surprised if SMB didn't support both symbolic and hard links, given the right server and client versions. Regards, Martin