The panel-backgroundcolor always is #000000 after relogin.
When changing the color, it is stored in the file
.gconf/apps/panel/profiles/default/panels/bottom_panel/%25gconf.xml.
When doing a relogin, this data doesn't appear to be read, the panel is
solid black.

<snip>

<entry name="panel_background_type" mtime="1056229306"
schema="/schemas/apps/panel/default_profiles/medium/panels/bottom_panel/panel_background_type"
muser="skotti" type="string">
<stringvalue>color-background</stringvalue>
</entry>

[...]

<entry name="panel_background_color" mtime="1056229306"
schema="/schemas/apps/panel/default_profiles/medium/panels/bottom_panel/panel_background_color"
muser="skotti" type="string">
<stringvalue>#3d64cc</stringvalue>
</entry>

</snip>