To launch VNC w/ GNOME put the following in your ~/.vnc/xstartup:
!/bin/sh [ -x /etc/vnc/xstartup ] && exec /etc/vnc/xstartup [ -r $HOME/.Xresources ] && xrdb $HOME/.Xresources $geometry = "1440x900" xsetroot -solid grey vncconfig -iconic & xterm -geometry 80x24+10+10 -ls -title "$VNCDESKTOP Desktop" & unset SESSION_MANAGER gnome-session &
And then run (for mac resolution 1440x900 on port 5900):
vncserver -geometry 1440x850 :2