please add mpfr package to EPEL too. it'd be very useful at least for EPEL-5. i'm just test mpfr-devel-2.3.1-1.fc9, rebuild in on EPEL-5 and compile without any problem. the only thing i change is: from: Requires: gmp >= 4.2.1 to Requires: gmp >= 4.1.4 since on rhel-5 this is the latest and even with this version all test are pass. so it's just a new branch request: https://fedoraproject.org/wiki/EPEL/FAQ#How_do_I_request_a_EPEL_branch_for_an_existing_Fedora_package.3F and a rebuild for you. thanks.
please ignore my request since in rhel gmp alrady contains mpfr:-)