It became tiresome not being able to see which version of Eclipse my OS X Dock icons leads to, so I quickly put together one for Luna and another for Mars using images picked from Wikipedia. On OS X one can easily replace an application icon by opening the application information dialog and simply dragging the new icon on top of the old. Note that because the Eclipse launcher will actually replace the icon once it has started, you also need to open the Eclipse.app folder and replace the file in Eclipse.app/Contents/Resources.

Feel free to use the icons, they’re at https://github.com/turesheim/eclipse-icons

I have no idea on how to do this on Linux and Windows but you can probably figure it out. If you do, please add the new versions to the git repository for others to enjoy.