
In these days there has been much fuzzing about the new browsing with files organizing themselves with the help of meta data. Maybe you ask yourself "What have this to do with the spatial browsing in gnome and how can it improve the browsing?". That's what I did. As I see it, the gnome people have introduced the spatial browsing so we are used to it when this new browsing is coming to town. This is very intelligent move of the gnome people and will help us adopt faster to this. This is when the spatial browsing is really making sense. I hope you see this when you've read this article.
My comment about networks was with respect to existing protocols that don't support (or whos usual configurations don't support) the type of metadata you are describing. For example the NFS', SMB, CIFS, AFS, etc. I'm sure that the Samba people (and MS, Apple, and everyone else) would not take kindly to being asked to rewrite things :-).
Protocols like WebDAV and FTP (more the way they are used than the protocols themselves) would stop working properly (in some ways).
The other point that can be made is standardised metadata is, IMHO, a bit of an oxymoron. Using something like the Dublin Core definitions will be overkill (in full capitals, using the blink, underline, bold AND italic tags) for almost all users. Similarly the semantic web stuff would probably not be suitable (due to the dependance on XML).
All one really needs is an extended attributes facility (which all real/useful/non-toy file systems have) and some useful list of standard attribute names and meanings. This would then make it an i18n nightmare and still not solve the searchability problem.