There's an option "Launch GNOME services on startup" in the Session and Startup settings. If it is used then a number of Gnome services start (it'd be nice to control which ones). It is however not possible to configure them with Gnome UI tools from within the XFCE afaik:

If I open gnome-control-center then there are only very few panels present, and all the important ones, such as keyboard settings, are missing. The reason for this is that the entry files for the panels in /usr/share/applications/ contain "OnlyShowIn=GNOME;Unity;" - if I add "XFCE;" to one of those then the corresponding panel shows properly and appears to work fine.

In my case the .desktop files come from the gnome-control-center package in Ubuntu Precise (1:3.4.1-0ubuntu2).

This is clearly a coexistence bug that cannot be blamed solely on XFCE, but nevertheless the option to run some Gnome services inside XFCE would be very useful. (In my case I need the Gnome keyring services, and I'd also like to use the Gnome keyboard shortcut handling, which as opposed to XFCE's handles abstract events like play/pause etc.)

Thanks.