Congratulations to my mate Alan, who has recently finished his first book - "Practical Rails Social Networking Sites". It's out now on Amazon, and is a must read if you're considering building anything in Rails.
"Practical Rails Social Networking Sites shows you the complete development cycle of a social networking community web site. The project develops first as a simple content management system, after which it progressively adds features in order to build a full Web 2.0--enabled community-based social networking site using Ruby on Rails".
"You will learn how to make the best use of the Ruby on Rails framework within a large project and how to implement and adapt features specific to a community. The book offers practical advice and tips for developing and testing, along with guidance on how to take your site live, as well as optimize and maintain it".
"The book also explores how to integrate with other community sites such as Flickr and Google Maps, and how to make good use of Rails' Ajax features. You will also learn how to optimize and adapt your site to work well on mobile browsers".