Comment 13 for bug 75882

No, it's not. Look at your output from Show. "Priority:" shows as Optional. Gnome-core is not a "Priority: Required" package. Its a meta-package that can be used to bring in one group's (Gnome developers? Debian?) idea of a base set of Gnome packages, but it is not essential. The Ubuntu folks have developed their own idea of what should be included as part of a Gnome system, and these would be the "Depends" portion of ubuntu-desktop. If you have ubuntu-minimal, ubuntu-standard, and ubuntu-desktop installed, you have everything you need for a functional Gnome desktop, without installing gnome-core.

I'm going to assume this was fixed since the Feisty era then, and reclose this bug.