The church planting section of the Leadership Network has some helpful articles and resources to browse through.  Be sure to check out their resources such as downloads, books, and podcasts. I should mention that I do not agree with some of the methodologies and approaches to church planting offered on LN; nevertheless, this is a good place to see where church planting has been, where it is going, and things we can learn (both how and how not to plant churches).  Their four main article are worth downloading (PDF):

Church Planting Overview
Funding New Churches
Improving the Health and Survivability of New Churches
Who Starts New Churches?