mpfr-devel-2.3.0-1.fc8 doesn't include libmpfr.a. gmp-devel-4.1.4-12.3 in F7 does include libmpfr.a.
There is trend to exclude static libraries - http://fedoraproject.org/wiki/Packaging/Guidelines#head-2302ec1e1f44202c9cc4bcce24cb711266557ad7 so it is ok. But if the static libraries are necessary for some package they could be added again but there have to be reason why this package can't use dynamic library. So if there is no such package then this is not a bug. If there is such a reason to add libmpfr.a please reopen this bug and write it here. Thanks.