So I installed Ubuntu GNOME 14.04 (which included GNOME 3.10) and noticed that GNOME Software Center isn't included and isn't available through the repositories. Then I tried installing Ubuntu 14.10 (which included GNOME 3.12 stack) and, you guessed it, no GNOME Software center. Only the Ubuntu Software center.
Any idea why the devs didn't include it even as an option? Isn't Ubuntu GNOME meant to be a vanilla-GNOME-type-of-distro?