Dwight Friesen, a theologian at Mars Hill Graduate School and a house-church planter, used a wonderful metaphor for the relationship between the church and its emerging edge during the COTA learning party. He's expanded upon it on his blog.
Dwight and I had some interesting conversation about Lutheran identity as a "two-edged sword." He offered that he's impressed that so many Lutherans he meets have really internalized that identity; we're obviously doing something right. But we have to be careful, we agreed, not to be so locked into a time or place or version of identity that we're not opening to what God is doing now.