As you probably already know, the MPI-3.0 document was published in September of 2012.

We even got a new logo for MPI-3.  Woo hoo!

The MPI Forum has been busy working on both errata to MPI-3.0 (which will be collated and published as "MPI-3.1") and all-new functionality for MPI-4.0.

The current plan is to finalize all errata and outstanding issues for MPI-3.1 in our December 2014 meeting (i.e., in the post-Supercomputing lull).  This means that we can vote on the final MPI-3.1 document at the next MPI Forum meeting in March 2015.

MPI is sometimes criticized for being "slow" in development.  Why on earth would it take 2 years to formalize errata from the MPI-3.0 document into an MPI-3.1 document?

The answer is (at least) twofold:

1. This stuff is really, really complicated.  What appears to be a trivial issue almost always turns out to have deeper implications that really need to be understood before proceeding.  This kind of deliberate thought and process simply takes time.
2. MPI is a standard.  Publishing a new version of that standard has a very large impact; it decides the course of many vendors, researchers, and users.  Care must be taken to get that publication as correct as possible.  Perfection is unlikely - as scientists and engineers, we absolutely have to admit that - but we want to be as close to fully-correct as possible.

MPI-4 is still "in the works".  Big New Things, such as endpoints and fault tolerant behavior is still under active development.  MPI-4 is still a ways off, so it's a bit early to start making predictions about what will/will not be included.