Standard Icon Naming Specification
One of the major components in establishing a look and feel for the desktop is the icon theme. This page explains the proposed standardisation of icon names to use when creating themes intended to work across all desktops and applications which implement the FreeDesktop.org Icon Naming Specification, which is intended to compliment the existing Icon Theme Specification. (docbook2html can be used to convert the xml to a more readable form).
Icon Naming Utilities
To help with the transition to the new naming scheme, Icon Mapping Utilities are available. This utility maps the icon names used by the GNOME and KDE desktops to the icon names proposed in the Icon Naming Specification linked above.