I've created a standalone app out of Nicolai's awesome app-search-widget with some modifications so that it can be hooked up to D-Bus scripts or hotkeys and used for keyboard shortcuts:

http://maemo.org/packages/view/app-search-app/

The app-search-app does not have a launcher icon and does not appear in the application list, but should be called from a script, like this:

The app UI is keyboard-friendly (discard the dialog with Backspace on the empty entry box, select with Enter and move between apps in the list with Left/Right and Up/Down while still being focused on the entry list). Useful with D-Bus scripts or something. I'm personally using modified-hildon-desktop with a slight modification (similar to this patch, only with "o" instead of "x" and the path to app-search-app instead of xterm) that maps the "o" key on the Desktop to this app, so I can just go to the Desktop, hit "o" and then start typing the app name and hit enter

And yes, the app is missing from the user/ section on purpose, and does not have an icon in the launcher, because it only makes sense if added to scripts (for everything else, you can use the original app-search-widget).