1) .desktop file should not use absolute path.

2a)  debian/rules should contain the following additional rule:

binary/gconf-cleaner::
        dh_desktop -p gconf-cleaner

2b)  Consider also using /usr/share/cdbs/1/class/gnome.mk

(Choose your favorite: 2a or 2b)

3)  You might want GCONF\(hyCLEANER instead of GCONF-CLEANER in the manpage

4)  Your debian/copyright should license the packaging, as:

The Debian packaging is (C) 2007, Jeremy Teale <orion@hypnogogic.org>
and is licensed under the GPL, see above.