There are two distinct “new” display control panels developed prior to the Longhorn reset. The first appeared in Milestone 3, and was removed in early Milestone 4. The second was present only in build 4093. Though both are created in the Avalon UI framework, it seems almost certain that the two efforts were not connected beyond their functionality and underlying technology.
Milestone 3 In build 3683, it is accessible out-of-the-box by right-clicking on the desktop and selecting Properties from the right click menu, as one would with any previous version of Windows.