Open MPI recently updated its version numbering scheme and development roadmap.
This new scheme aims to provide more semantic information in the Open MPI "A.B.C" version number to both end users and system administrators.
There are a number of details worth understanding about the new version number scheme, but we recognize that many people won't want to read a detailed description of the plan. So here's the TL;DR version:
For those of you wanting to see more detail, the following slides explain things more fully: