Gnome developers are working on a model that allows a user to search everything and anything right from Gnome search box. This will hopefully be integrated in the next big Gnome release, Gnome 3.8. Gnome 3.8 is scheduled to release next year with some new apps and a hell lot of improvements.
We have already covered how the search will look like. The Gnome developers have developed a settings panel which lets you configure which areas or apps to search, thus giving you more freedom of choice and control over your system.
You can search Contacts, Files, Documents and Boxes along with apps. The feature also searches packages from the software repositories and offers you one click installation of apps.
The feature is not mature yet and is currently under development. Much like Unity, which follows the integrated search feature for files, videos, pictures and apps, this will make it easier for the users to access what they want with just a keypress.
We hope that this will become the next big thing in Gnome. Gnome shell already supports apps, contacts and file search via the tracker extension. Adding more elements in the search criteria will make it more mature.