I would answer it like this: For a Linux user, you can already build such a system yourself quite trivially by getting an FTP account, mounting it locally with

I would answer it like this: For a Linux user, you can already build such a system yourself quite trivially by getting an FTP account, mounting it locally with curlftpfs, and then using SVN or CVS on the mounted filesystem. From Windows or Mac, this FTP account could be accessed through built-in software.