Ed Stetzer has been writing a lot about missional ecclesiology from within the Southern Baptist Convention. He is not a lone voice, but among Convention leaders he is the most vocal and articulate. In the Pastor's Edtion of the most recent On Mission Magazine Ed answers the question, "What is a Missional Church?" This new article functions like a primer on missional thought (scroll about half way down the linked page).
A few quotes:
Why all the fuss over a word [missional]? Can't a church do what it's been called to do for more than two millennia and not mess with semantics? It certainly can. But, the reason is not the word, it's the emphasis. Churches are discovering the need to be missional in their communities. So, the important question is, "What is a missional church?"
[Missional churches] do the things that missionaries do, regardless of the context. They can be parachute-dropped into a village in India, or into the hustle of any North American city and be missional. They study and learn a culture, live and proclaim the good news and contextualize it for that culture. Missional churches take Acts 1:8 literally and act like missionaries--sharing the gospel in word and deed--in their own Jerusalem (city or area), Judea (state or region), Samaria (North America) and to the ends of the earth.
He explains that missional churches are incarnational, indigenous, and intentional and gives a paragraph for each characteristic. The article is good and can be helpful as an introduction to the topic.
As critical as missional ecclesiology is to the health of our churches and therefore our Convention, it does not answer all the questions. But if we get this wrong, everything else is lost. If you are looking to get a grasp on the missional church read Ed's article at OnMission.com. You can also read my short posts on the subject beginning here.
Ed also has two books coming out in may on this subject - both published by Broadman and Holman (a division of Lifeway); Planting Missional Churches and Breaking the Missional Code, co-authored by Ed Stetzer & David Putman.