A member of Neowin, BananaHammock, has found some interesting things from previous and present Longhorn builds. Included are some DirectX objects found in shell32.dll, browseui.dll, and others.
There are also some aero concept pictures from Kerry Hammil. They depict a conceptual DWM border which would normally reside in the aero.theme file or perhaps uxdesk.dll.
Check them out below.