desktop environments / x / window managers?

Have I got this right?

* X is the graphical server for linux.
* you run window managers on top of X, window managers can be minimal (blackbox) or fuller featured.

So, what are Gnome and KDE?  Are they a combination of WM and extra software, or are they just feature rich WMs?

And since has came a new concept called "desktop shell" with Enlightenment (E17 one), it will be released in the DVD bonus of Duke Nukem Forever (along with a working operating system based on Hurd)