When building with shared-libraries version of mpi,
there are still bugs in the mpich 1.2.5 script wrapper mpiCC.
Here's a config line that works for the rpm version as of
jan 2003:

./configure  --with-boost=/usr/local/include --with-mpi=/usr/local/cca --with-cca-classic=/usr/local --with-cca-babel=/usr/local --prefix=/usr/local '--with-mpi-cxx=/usr/local/cca/bin/mpiCC -shlib -Wl,-rpath,/usr/local/cca/lib'

contrary to comments from bill gropp, -shlib doesn't affect the outcome,
and can be omitted.