Short review: This is the only book I know of that is particularly about leading prayer in a small group/community group setting. Very practical in its orientation. He uses lots of prayers as examples of both positive and negative ways to approach prayer in a small group setting. Basic idea is that setting matters and that the prayers that you pray alone or in a large group setting are not the prayers you should be praying in a small group setting.

My longer review is on my blog at http://bookwi.se/prayer/