Before everyone clamors "use SSH", this is NOT a server. I've to use the server images because I couldn't find the ubuntu desktop images. The EC2 virtual machine/instance will be used like a shared desktop (between 2 people) but in the cloud. Yes, they will log via the same username/password so they intentionally share the same desktop etc.
Whew, so how would I go about doing this? I've already run
sudo aptitude install x-window-system-core gnome-core
sudo apt-get install --no-install-recommends ubuntu-desktop
BTW, the second command appears to be a superset of the first, so just the second should have been ok. Anyway, I suspect I'm missing something more, like enabling the XDMCP client on the 'server' or the VNC server on the 'server' (either option is ok, I've more familiar with VNC) or NX (quick like Windows RDP).