I, as maintainer of the Debian packages, want to keep the deskbar-applet package separate. There are several reasons for this, the most important one is, that I don't want to force people to install the complete python/python-gtk stack (which is necessary for deskbar-applet), if people only want to run tracker-search-tool.
I don't know exactly how depencies work on Debian, but the above statement is not entirely true; tracker-deskbar.py doesn't have a hard-dependency on deskbar-applet, it acts sort of like a plugin. I don't have deskbar-applet installed on my fedora system, and tracker-0.5.4 (with tracker-deskbar.py installed) runs just fine here. Deji