Perhaps no answer to your question but I can share some user experiences.
This (warning messages) is what I also see when I try to
uninstall/install (renew/update) individual octave-forge packages in
Mandriva (2010.1).
Mandriva has made renewal/updating individual octave-forge packages a
cumbersome process, with unexpected dependencies all over the place,
perhaps due to the still "monolithic" character of its octave-forge
rpm, and rpm and (octave's) pkg stepping onto each other's toes.
Hopefully you can make it much easier for Fedora users, up to the
point that rpm isn't needed (or only needed for initial installation),
i.e., so that just Octave's pkg command will do. (I'd prefer pkg over
rpm in this case.)
I think development of octave-forge packages proceeds more rapidly
than rpm's can be built, tested & updated - if you automate building
rpms from individual octave-forge packages this can be alleviated a bit.
Thus either Q-control by Fedora will be hampered, or octave users will
be withheld a bit from trying the newest octave-forge packages (in
turn, hampering package development) if they must wait until tested
rpms become available.
FYI, "pkg" has an option "forge" that will d/l & install octave-forge
packages directly from octave.sf.net. Permissions (root) may interfere
when packages go into /usr/[local/]share, but that's probably resolvable.
P.