Thanks for your replies!
Actually I just wanted to access the Services panel of Gnome so that I can disable some of the services started at Gnome boot.. in an attempt to speed up its launch.

Right now Gnome takes quite some time to load completely (I'm starting gnome from Maemo, as per Qole), what I get is white screen, then black screen, then "X" cursor, then the Gnome top & bottom panels, then the Gnome menu & panel items appear (that part is fine, relatively fast), then it seems to hang, and after 1.5 or 2 minutes, the background appears, and some seconds after that, the desktop icons.

So yeah, I just wished I could prevent some services to launch in order to speed up the boot process.