GHacks.net posted a guide about using the KDE 4.5 search and launch containment activity

If you have experienced GNOME 3 yet then you have a fairly good example for what Search and Launch is. In the GNOME 3 desktop, when you have the Activities Menu open that is, effectively what Search and Launch is. The Search and Launch Activity allows you to search through your desktop for whatever you need to find and view, launch, or use the results. It’s a fairly amazing tool that will make your desktop experience all the more efficient. So much so, you might wander, with the Search and Launch Activity, why did the Developers keep the old Panel lying around.

Let’s see how to include Search and Launch on your desktop.

  Using the KDE 4.5 Search and Launch Containment Activity