shawn@work:~ $ date && gconftool-2 -R /desktop/gnome/background
Mon Apr  9 10:42:57 CDT 2007
 primary_color = #76848F
 color_shading_type = solid
 secondary_color = #7F7F7F
 picture_filename =
 picture_options = none
 picture_opacity = 100
 draw_background = true
shawn@work:~ $ gconftool-2 --type string --set /desktop/gnome/background/primary_color '#000000'
shawn@work:~ $ date && gconftool-2 -R /desktop/gnome/background
Mon Apr  9 10:43:09 CDT 2007
 primary_color = #76848F
 color_shading_type = solid
 secondary_color = #7F7F7F
 picture_filename =
 picture_options = none
 picture_opacity = 100
 draw_background = true
shawn@work:~ $