OK, I have now figured out how to successfully build pbbuttonsd-0.7.2-1.ppc.rpm from http://www.itux.net/rpm/srpms/pbbutt....7.2-1.src.rpm
on FC5 ppc:
First, it must be ensured that the kernel-devel package is installed (to provide 'radeonfb.h').
rpm -ivh pbbuttonsd-0.7.2-1.src.rpm
edit '/usr/src/redhat/SPECS/pbbuttonsd.spec' to include
# workaround for radeonfb.h in src/module_display.c
#export CPPFLAGS="-include /usr/include/linux/cdrom.h -I/lib/modules/`uname -r`/build/include"
mkdir ./linux; ln -s /lib/modules/`uname -r`/build/include/linux/radeonfb.h ./linux/
rpmbuild -bb /usr/src/redhat/SPECS/pbbuttonsd.spec