Obviously, nautilus needs it, but there's a way (always a way) to disable it in the USE flag. http://gentoo-portage.com/gnome-base/nautilus/USE#ptabs
Next time Sabayon is doing a release, compile nautilus without the tracker and beagle USE flag, so Sabayon lovers won't feel like they are using Windows.
The easy way to turn it off to see what difference it makes is through System \ Preferences \ Indexing Preferences and unchecking the "Enable indexing" option. The deskbar USE flag makes searching convenient http://gentoo-portage.com/app-misc/tracker/USE#ptabs