Virtual VNC screen/workspace

If you are using FreeVNC:

If say your computer name is comp-user-01. You can VNC into a different session by using: comp-user-01:1

I believe you can set how many simultaneous users within the VNC server settings.

Edit: You can replace the last 1 with the number of the session you want to log into.

Connect as discussed in Sakamoto Kazuma's answer.

You'll need an xstartup script in ~/.vnc/xstartup. It may already be there. If not, the standard one looks like:

#!/bin/sh

# Uncomment the following two lines for normal desktop:
# unset SESSION_MANAGER
# exec /etc/X11/xinit/xinitrc

[ -x /etc/vnc/xstartup ] && exec /etc/vnc/xstartup
[ -r $HOME/.Xresources ] && xrdb $HOME/.Xresources
xsetroot -solid grey
vncconfig -iconic &
xterm -geometry 80x24+10+10 -ls -title "$VNCDESKTOP Desktop" &
twm &

Now, uncomment the two lines starting with "# unset " and "# exec " (yeah-- those two just below the comment that says "Uncomment the following two lines for normal desktop"

That should give you your normal, Gnome desktop.