Rmpi failing to install with all latest MPI packages and config arguments

On FC10 with openmpi and mpich2 installed, the command "R CMD INSTALL
Rmpi_0.5-7.tar.gz --configure-args=--with-mpi=/usr/lib64/openmpi" (or
/usr/lib64/mpich2) fails with the error ''cannot find mpi.h".  Doing a
(s)locate indicates no header file labeled as such. Would appreciate
any trailheads.

TIA,

V.

Vince Fulco, CFA, CAIA
612.424.5477 (universal)
vfulco1 at gmail.com