I'm about to build the Makefile for Parallel::MPI::Simple.

If you find you cannot build this module, or that the tests fail, you
may be on an odd system where you need to do more than pass -lmpi to
your C compiler to build MPI applications.  If this is the case, rerun
perl Makefile.PL with appropriate LDFLAGS= and CCFLAGS= arguments.

Also, this module is very new so if you manage to get it working on one
of the systems not listed in INSTALL I'd love to hear about it.
Checking if your kit is complete...
Looks good
Note (probably harmless): No library found for -lmpi
Writing Makefile for Parallel::MPI::Simple
cp ic.pl blib/lib/Parallel/MPI/ic.pl
cp Simple.pm blib/lib/Parallel/MPI/Simple.pm
/Users/cpanrun/pristine/5.8.7/bin/perl /Users/cpanrun/pristine/5.8.7/lib/5.8.7/ExtUtils/xsubpp  -typemap /Users/cpanrun/pristine/5.8.7/lib/5.8.7/ExtUtils/typemap  Simple.xs > Simple.xsc && mv Simple.xsc Simple.c
gcc -c   -fno-common -DPERL_DARWIN -no-cpp-precomp -arch ppc -arch i386 -nostdinc -B/Developer/SDKs/MacOSX10.4u.sdk/usr/include/gcc -B/Developer/SDKs/MacOSX10.4u.sdk/usr/lib/gcc -isystem/Developer/SDKs/MacOSX10.4u.sdk/usr/include -F/Developer/SDKs/MacOSX10.4u.sdk/System/Library/Frameworks -mmacosx-version-min=10.3 -DUSE_SITECUSTOMIZE -DNO_HASH_SEED -fno-strict-aliasing -pipe -O3   -DVERSION=\"0.03\" -DXS_VERSION=\"0.03\"  "-I/Users/cpanrun/pristine/5.8.7/lib/5.8.7/darwin-thread-multi-2level/CORE"   Simple.c
Simple.xs:8:18: error: mpi.h: No such file or directory
Simple.xs: In function '_Bcast':
Simple.xs:24: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs:24: error: (Each undeclared identifier is reported only once
Simple.xs:24: error: for each function it appears in.)
Simple.xs:27: error: 'MPI_INT' undeclared (first use in this function)
Simple.xs:28: error: 'MPI_CHAR' undeclared (first use in this function)
Simple.xs: In function '_Send':
Simple.xs:51: error: 'MPI_INT' undeclared (first use in this function)
Simple.xs:51: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs:52: error: 'MPI_CHAR' undeclared (first use in this function)
Simple.xs: In function '_Recv':
Simple.xs:63: error: 'MPI_Status' undeclared (first use in this function)
Simple.xs:63: error: parse error before 'tstatus'
Simple.xs:68: error: 'MPI_INT' undeclared (first use in this function)
Simple.xs:68: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs:68: error: 'tstatus' undeclared (first use in this function)
Simple.xs:71: error: 'MPI_CHAR' undeclared (first use in this function)
Simple.xs: In function '_Comm_rank':
Simple.xs:87: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs: In function '_Comm_size':
Simple.xs:94: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs: In function 'COMM_WORLD':
Simple.xs:100: error: 'MPI_COMM_WORLD' undeclared (first use in this function)
Simple.xs: In function 'Barrier':
Simple.xs:105: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs: In function '_Gather':
Simple.xs:128: error: 'MPI_Status' undeclared (first use in this function)
Simple.xs:128: error: parse error before 'tstatus'
Simple.xs:134: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs:138: error: 'MPI_INT' undeclared (first use in this function)
Simple.xs:151: error: 'MPI_CHAR' undeclared (first use in this function)
Simple.xs:152: error: 'tstatus' undeclared (first use in this function)
Simple.xs: In function '_Comm_compare':
Simple.xs:174: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs:176: error: 'MPI_IDENT' undeclared (first use in this function)
Simple.xs:178: error: 'MPI_CONGRUENT' undeclared (first use in this function)
Simple.xs:180: error: 'MPI_SIMILAR' undeclared (first use in this function)
Simple.xs:182: error: 'MPI_UNEQUAL' undeclared (first use in this function)
Simple.xs: In function '_Comm_free':
Simple.xs:191: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs:191: error: parse error before ')' token
Simple.xs:192: error: 'MPI_COMM_NULL' undeclared (first use in this function)
Simple.xs: In function '_Comm_dup':
Simple.xs:197: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs:197: error: parse error before 'newcomm'
Simple.xs:198: error: 'newcomm' undeclared (first use in this function)
Simple.xs: In function '_Comm_split':
Simple.xs:203: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs:203: error: parse error before 'newcomm'
Simple.xs:206: error: 'MPI_UNDEFINED' undeclared (first use in this function)
Simple.xs:207: error: 'newcomm' undeclared (first use in this function)
Simple.xs:8:18: error: mpi.h: No such file or directory
Simple.xs: In function '_Bcast':
Simple.xs:24: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs:24: error: (Each undeclared identifier is reported only once
Simple.xs:24: error: for each function it appears in.)
Simple.xs:27: error: 'MPI_INT' undeclared (first use in this function)
Simple.xs:28: error: 'MPI_CHAR' undeclared (first use in this function)
Simple.xs: In function '_Send':
Simple.xs:51: error: 'MPI_INT' undeclared (first use in this function)
Simple.xs:51: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs:52: error: 'MPI_CHAR' undeclared (first use in this function)
Simple.xs: In function '_Recv':
Simple.xs:63: error: 'MPI_Status' undeclared (first use in this function)
Simple.xs:63: error: parse error before 'tstatus'
Simple.xs:68: error: 'MPI_INT' undeclared (first use in this function)
Simple.xs:68: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs:68: error: 'tstatus' undeclared (first use in this function)
Simple.xs:71: error: 'MPI_CHAR' undeclared (first use in this function)
Simple.xs: In function '_Comm_rank':
Simple.xs:87: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs: In function '_Comm_size':
Simple.xs:94: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs: In function 'COMM_WORLD':
Simple.xs:100: error: 'MPI_COMM_WORLD' undeclared (first use in this function)
Simple.xs: In function 'Barrier':
Simple.xs:105: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs: In function '_Gather':
Simple.xs:128: error: 'MPI_Status' undeclared (first use in this function)
Simple.xs:128: error: parse error before 'tstatus'
Simple.xs:134: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs:138: error: 'MPI_INT' undeclared (first use in this function)
Simple.xs:151: error: 'MPI_CHAR' undeclared (first use in this function)
Simple.xs:152: error: 'tstatus' undeclared (first use in this function)
Simple.xs: In function '_Comm_compare':
Simple.xs:174: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs:176: error: 'MPI_IDENT' undeclared (first use in this function)
Simple.xs:178: error: 'MPI_CONGRUENT' undeclared (first use in this function)
Simple.xs:180: error: 'MPI_SIMILAR' undeclared (first use in this function)
Simple.xs:182: error: 'MPI_UNEQUAL' undeclared (first use in this function)
Simple.xs: In function '_Comm_free':
Simple.xs:191: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs:191: error: parse error before ')' token
Simple.xs:192: error: 'MPI_COMM_NULL' undeclared (first use in this function)
Simple.xs: In function '_Comm_dup':
Simple.xs:197: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs:197: error: parse error before 'newcomm'
Simple.xs:198: error: 'newcomm' undeclared (first use in this function)
Simple.xs: In function '_Comm_split':
Simple.xs:203: error: 'MPI_Comm' undeclared (first use in this function)
Simple.xs:203: error: parse error before 'newcomm'
Simple.xs:206: error: 'MPI_UNDEFINED' undeclared (first use in this function)
Simple.xs:207: error: 'newcomm' undeclared (first use in this function)
lipo: can't open input file: /var/tmp//cc1KIxdo.out (No such file or directory)
make: *** [Simple.o] Error 1