The MPICH folks have released an RC candidate for MPICH 3.0:
A new preview release of MPICH, 3.0rc1, is now available for download. The primary focus of this release is to provide full support for the MPI-3 standard. Other smaller features including support for ARM v7 native atomics are also included.
Two smaller items to note:
Congratulations to the MPICH crew for this release!