In Ubuntu 12.10, the developers implemented the Unity Previews, a fancy intuitive manner of accessing details about applications, files, harddisk partitions, available-for-purchase Ubuntu One Music Store items, etc, basically, right-clicking on an item from the Dash, opens it in its dedicated Preview view.
Along with the Previews, the developers landed ghost icons, ghost icons that express/display items available in a specific lens, like for instance, right-clicking on an application from Unity Applications lens, opens the clicked app via a specific Preview and populates the Dash's top and bottom areas with vividless (almost invisible/barely noticeable) icons, ghost icons that lack functionality (in Ubuntu 12.10).
It seems that the ghost-items approach is to be probably further enhanced in the upcoming Ubuntu 13.04, enhanced in the sense of receiving functionality/purpose.
The latest Unity code landed in its official launchpad page exposes a new set of Dash animations, bearing a definitely interesting look & feel, animations that refine the Dash interactions and visually link the Unity Previews with ghost items.
Right-clicking on an item, opens it in its Preview, yet, the Preview is rendered with a dark-ish visual container, properly differentiating the actual details-wise Preview from the ghost items.
The ghost items are now more accurately aligned, furthermore, navigating through Previews, highlights linked ghost items, meaning, while System Monitor is previewed, the ghost icon (representing System Monitor) is highlighted, clicking the Preview's navigation icons (thus changing the Preview with new apps), visually updates the ghost images.
Furthermore, the Preview is attached (with an up-pointed arrow) to its ghost, expressing a tooltip-like look; if the previewed item is located on the top-right corner of the Dash, the up-pointed arrow comes from the top-right ghost.