With reference to former discussions about recent changes in GNOME First Steps (http://www.funtoo.org/Talk:GNOME_First_Steps) :

The following lines were added in the underlying page as a workaround for someone that was prevented from logging in :

rc-update add consolekit default
rc-update add dbus default

I did not experience this bugs myself (since I don't use Gnome), but according to drobbins answer, this should be considered as a bug :

GNOME should be mergeable by simply setting the desktop profile, enabling the gnome mix-in, and emerging GNOME. If this doesn't work, then it's a bug, and a bug should be filed.