Standard Icon Naming Specification
One of the major components to creating a look and feel for the desktop, is the Icon Theme. This page explains the proposal of standardizing on icon names to use when creating themes, to work across all desktops and applications which implement the FreeDesktop.org Icon theme Specification (ON the gnome desktop, you can use yelp to view the docbook file in a readable form).
Icon Naming Utilities
To help with the transition to the new naming scheme, a legacy icon mapping utilities are available. It will map the new names to the legacy names used by the GNOME and KDE desktops.