1. 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.
I snorted audibly when I imagined explaining this approach to my non-techie colleagues.
And, in my case, it did actually replaced my USB drive 99% of its uses. The only time in the last 2 years that I used it was to go to print some PPT on a printing shop, as I don't have a printer at home. And I had to search the whole house to find my USB driver (which was lost on an old backpack).