I'm running numerous Kickstart installs of Fedora 9 final.  These are heavily
stripped-down minimal machines -- no X at all, anything GUI-related is left off.
 So the Kickstart files have very specific package lists.

One box is a development box, so the goal was to install the mandatory
Development Tools packages (all of which are needed), and then a select few
additional packages.  This part of the Kickstart file %packages entry looks like
this:

  @Development Tools --nodefaults
  elfutils
  cpan2rpm
  ltrace
  patchutils
  subversion
  valgrind

What ends up happening is, anything that is normally a default selection for
that group fails to install, even if the package was specifically named later
on.  It appears to handle the --nodefaults option last, and then removes any
package that is on the default list.

If you use the particular %packages snippet above, you'll get the mandatory
Development Tools packages (as expected), but it fails to install elfutils,
ltrace, patchutils, subversion, and valgrind.  All 5 of those are defaults for
the Development Tools group.  cpan2rpm, on the other hand, does get installed,
as it's normally an optional package.