It might not have been mature enough to ship in Ubuntu 13.04, but work on enhancing the "Smart Scopes Service" continues apace.
Unity's Previews feature has seen a number of refinements over the last week as work on Unity in 13.04 continues. A slicker animation has been introduced, along with better visual differentiation between the active and inactive preview items. If you're a subscriber to our YouTube channel then you'll have seen a video of these tweaks in action yesterday.
Exciting new features are getting ready to land in the development builds of Unity in Ubuntu 12.10. Amongst them is a new preview feature called, unimaginatively, 'Previews'.