Weston has a VNC server built in. Then if you have a desktop environment which uses Weston you'll be able to use VNC. What has been added to the spec is being

Weston has a VNC server built in. Then if you have a desktop environment which uses Weston you'll be able to use VNC. What has been added to the spec is being able to run one "compositor" in another. So you can have KDE/Enlightment running within/under Weston. I don't think that is the approach taken by GNOME though. Not sure if it'll be session specific or not.