Why do we still follow the 'Folder' metaphor?
ElliotH: The problem is this needs to be an change throughout an operating system or it doesn't work.I know there have been userspace file system projects for Linux systems that have attempted the tagging system, but  none have really become mainstream. Gnome seems to be going in the direction of time-pased file sorting which is another non-folder oriented way of thinking.On the Apple side I think they really want their users to be searching in preference to tagging.Microsoft had a go with Windows 7, but obviously they want users to be able to upgrade their old operating system making it impractical to make it a global default.But the other thing to consider is 'Cloud' computing, a lot of online services (eg Google's) use tagging rather than a folder modal. This means if software moves more online/browser based we'll see tag-based systems emerge naturally.Edit: Fixed some typos