Testing with Lenny D-I RC1 CDs has shown that using the gnome meta package as
key results in two server tasks getting pushed off CD1 for i386. Having such
a big key package also creates a real risk that Gnome will not be installable
at all if only CD1 is used because "key" packages are not available.
Switch back to using gnome-desktop-environment as key, but keep gnome as first
non-key package so that the total install will remain the same for installs
where additional sources (mirror, CD2) are available or DVD installs.
Using gnome-desktop-environment reduces the pressure on CD1 by ~60MB.