How can I run two instance of, e.g. GNOME, on my computer at once? I know how to change the virtual terminal, but I can't work out how to start a second instance of gnome - it just exits telling me that the X session is locked.
EDIT: The other thing that I would really like to know is how to run two different desktops at once - e.g. XFCE and GNOME. I know that I can change the default desktop in .xinitrc or something like that, but then I would have to do so every time - is there any way to select the desktop type when creating the new XSession?