I could write another very long post that provided the history behind the present missional impulse - while debating / explaining the desire to either define it or contain it.
We could talk / debate ad nauseum about David Boesch, Lesslie Newbigin, the UK and US versions of the Gospel and Our Culture Network, Missio Dei, missional from a Reformed perspective / Arminian perspective or any number of the finer aspects of "missional". And, at one level, this might be a rather important part of the discussion as we learn how to disciple a mission-shaped people.
But at another level, it is simply more talk - when what we need to do is simplify the talk so that people might consider being formed as mission-shaped.
A suggested Missional KISS
The Word became flesh and blood, and moved into the neighborhood. And that is what He is calling us to do.
The first sentence is from Eugene Peterson's poetic transliteration of John 1:14
And for those who don't recognize the acronym KISS.