According to the recommendations at http://www.w3.org/Addressing/URL/4_URI_Recommentations.html:

Reserved characters
  Hierarchical forms
    The slash ("/", ASCII 2F hex) character is reserved for the delimiting of
substrings whose relationship is hierarchical.
[...]
  Note
    The similarity to unix and other disk operating system filename conventions
should be taken as purely coincidental, and should not be taken to indicate
that URIs should be interpreted as file names.

So, if you want the hierarchical scheme for your URIs to match that of your file system, you should use the forward slash - but not because it's the UNIX way of doing things.

For other stuff on the site, please go here.