"And let us consider how to stir up one another to love and good works, not neglecting to meet together, as is the habit of some, but encouraging one another, and all the more as you see the Day drawing near." (Hebrews 10:24-25)
You can almost call "missional communities" a trend. It even made it to wikipedia. You can almost call it that, except that the connotation of a trend is something fleeting and superficial and from what I have seen these groups are anything but.