There are already a number of lenses under development. Will the search results for these lenses be included in the main unity dashboard search?
Third party lenses can control whether their results are included in the main dashboard search by ShowGlobal & ShowEntry keys in the .place file for the lens. There doesn't currently appear to be a UI option for setting this.
See https://wiki.ubuntu.com/Unity/Lenses#Registration for information about the .place file.