Things I'd like to add. Assuming these are actually possible.
%_smp_ncpus_max for EL5
python2 macros for EL6 and EL5
%__global_ldflags in EL6 (and maybe EL5)
Requires redefinition of %cmake, %cmake_kde4, %qmake_qt4 and %configure
%make_build for EL6 and EL5